[PATCH v1 1/4] net: ti: netcp: restore get/set_pad_info() functionality

From: Arnd Bergmann <arnd@arndb.de>

The commit 899077791403 ("netcp: try to reduce type confusion in
descriptors") introduces a regression in Kernel 4.5-rc1 and it breaks
get/set_pad_info() functionality.

The TI NETCP driver uses pad0 and pad1 fields of knav_dma_desc to
store DMA/MEM buffer pointer and buffer size respectively. And in both
cases for Keystone 2 the pointer type size is 32 bit regardless of
LAPE enabled or not, because CONFIG_ARCH_DMA_ADDR_T_64BIT originally
is not expected to be defined.

			!LAPE	LPAE
sizeof(void*)		32bit	32bit
sizeof(dma_addr_t) 	32bit	32bit
sizeof(phys_addr_t) 	32bit	64bit

Unfortunately, above commit changed buffer's pointers save/restore
code (get/set_pad_info()) and added intermediate conversation to u64
which works incorrectly on 32bit Keystone 2 and causes TI NETCP driver
crash in RX/TX path due to "Unable to handle kernel NULL pointer"
exception. This issue was reported and discussed in [1].

Hence, fix it by partially reverting above commit and restoring
get/set_pad_info() functionality as it was before.

[1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95361.html
Cc: Wingman Kwok <redacted>
Cc: Mugunthan V N <redacted>
CC: David Laight <redacted>
Reported-by: Franklin S Cooper Jr <redacted>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Murali Karicheri <redacted>
---
 v1 - Just fixed a checkpatch warning for commit description
 drivers/net/ethernet/ti/netcp_core.c | 59 +++++++++++-------------------------
 1 file changed, 18 insertions(+), 41 deletions(-)

diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c
index c61d66d..0b26e52 100644
--- a/drivers/net/ethernet/ti/netcp_core.c
+++ b/drivers/net/ethernet/ti/netcp_core.c

@@ -117,20 +117,10 @@ static void get_pkt_info(dma_addr_t *buff, u32 *buff_len, dma_addr_t *ndesc,
 	*ndesc = le32_to_cpu(desc->next_desc);
 }
 
-static void get_pad_info(u32 *pad0, u32 *pad1, u32 *pad2, struct knav_dma_desc *desc)
+static void get_pad_info(u32 *pad0, u32 *pad1, struct knav_dma_desc *desc)
 {
 	*pad0 = le32_to_cpu(desc->pad[0]);
 	*pad1 = le32_to_cpu(desc->pad[1]);
-	*pad2 = le32_to_cpu(desc->pad[2]);
-}
-
-static void get_pad_ptr(void **padptr, struct knav_dma_desc *desc)
-{
-	u64 pad64;
-
-	pad64 = le32_to_cpu(desc->pad[0]) +
-		((u64)le32_to_cpu(desc->pad[1]) << 32);
-	*padptr = (void *)(uintptr_t)pad64;
 }
 
 static void get_org_pkt_info(dma_addr_t *buff, u32 *buff_len,

@@ -163,11 +153,10 @@ static void set_desc_info(u32 desc_info, u32 pkt_info,
 	desc->packet_info = cpu_to_le32(pkt_info);
 }
 
-static void set_pad_info(u32 pad0, u32 pad1, u32 pad2, struct knav_dma_desc *desc)
+static void set_pad_info(u32 pad0, u32 pad1, struct knav_dma_desc *desc)
 {
 	desc->pad[0] = cpu_to_le32(pad0);
 	desc->pad[1] = cpu_to_le32(pad1);
-	desc->pad[2] = cpu_to_le32(pad1);
 }
 
 static void set_org_pkt_info(dma_addr_t buff, u32 buff_len,

@@ -581,7 +570,6 @@ static void netcp_free_rx_desc_chain(struct netcp_intf *netcp,
 	dma_addr_t dma_desc, dma_buf;
 	unsigned int buf_len, dma_sz = sizeof(*ndesc);
 	void *buf_ptr;
-	u32 pad[2];
 	u32 tmp;
 
 	get_words(&dma_desc, 1, &desc->next_desc);

@@ -593,14 +581,12 @@ static void netcp_free_rx_desc_chain(struct netcp_intf *netcp,
 			break;
 		}
 		get_pkt_info(&dma_buf, &tmp, &dma_desc, ndesc);
-		get_pad_ptr(&buf_ptr, ndesc);
+		get_pad_info((u32 *)&buf_ptr, &buf_len, ndesc);
 		dma_unmap_page(netcp->dev, dma_buf, PAGE_SIZE, DMA_FROM_DEVICE);
 		__free_page(buf_ptr);
 		knav_pool_desc_put(netcp->rx_pool, desc);
 	}
-
-	get_pad_info(&pad[0], &pad[1], &buf_len, desc);
-	buf_ptr = (void *)(uintptr_t)(pad[0] + ((u64)pad[1] << 32));
+	get_pad_info((u32 *)&buf_ptr, &buf_len, desc);
 
 	if (buf_ptr)
 		netcp_frag_free(buf_len <= PAGE_SIZE, buf_ptr);

@@ -639,8 +625,8 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 	dma_addr_t dma_desc, dma_buff;
 	struct netcp_packet p_info;
 	struct sk_buff *skb;
-	u32 pad[2];
 	void *org_buf_ptr;
+	u32 tmp;
 
 	dma_desc = knav_queue_pop(netcp->rx_queue, &dma_sz);
 	if (!dma_desc)

@@ -653,8 +639,7 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 	}
 
 	get_pkt_info(&dma_buff, &buf_len, &dma_desc, desc);
-	get_pad_info(&pad[0], &pad[1], &org_buf_len, desc);
-	org_buf_ptr = (void *)(uintptr_t)(pad[0] + ((u64)pad[1] << 32));
+	get_pad_info((u32 *)&org_buf_ptr, &org_buf_len, desc);
 
 	if (unlikely(!org_buf_ptr)) {
 		dev_err(netcp->ndev_dev, "NULL bufptr in desc\n");

@@ -679,7 +664,6 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 	/* Fill in the page fragment list */
 	while (dma_desc) {
 		struct page *page;
-		void *ptr;
 
 		ndesc = knav_pool_desc_unmap(netcp->rx_pool, dma_desc, dma_sz);
 		if (unlikely(!ndesc)) {

@@ -688,8 +672,7 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 		}
 
 		get_pkt_info(&dma_buff, &buf_len, &dma_desc, ndesc);
-		get_pad_ptr(&ptr, ndesc);
-		page = ptr;
+		get_pad_info((u32 *)&page, &tmp, ndesc);
 
 		if (likely(dma_buff && buf_len && page)) {
 			dma_unmap_page(netcp->dev, dma_buff, PAGE_SIZE,

@@ -767,6 +750,7 @@ static void netcp_free_rx_buf(struct netcp_intf *netcp, int fdq)
 	unsigned int buf_len, dma_sz;
 	dma_addr_t dma;
 	void *buf_ptr;
+	u32 tmp;
 
 	/* Allocate descriptor */
 	while ((dma = knav_queue_pop(netcp->rx_fdq[fdq], &dma_sz))) {

@@ -777,7 +761,7 @@ static void netcp_free_rx_buf(struct netcp_intf *netcp, int fdq)
 		}
 
 		get_org_pkt_info(&dma, &buf_len, desc);
-		get_pad_ptr(&buf_ptr, desc);
+		get_pad_info((u32 *)&buf_ptr, &tmp, desc);
 
 		if (unlikely(!dma)) {
 			dev_err(netcp->ndev_dev, "NULL orig_buff in desc\n");

@@ -829,7 +813,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 	struct page *page;
 	dma_addr_t dma;
 	void *bufptr;
-	u32 pad[3];
+	u32 pad[2];
 
 	/* Allocate descriptor */
 	hwdesc = knav_pool_desc_get(netcp->rx_pool);

@@ -846,7 +830,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 				SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 
 		bufptr = netdev_alloc_frag(primary_buf_len);
-		pad[2] = primary_buf_len;
+		pad[1] = primary_buf_len;
 
 		if (unlikely(!bufptr)) {
 			dev_warn_ratelimited(netcp->ndev_dev,

@@ -858,9 +842,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 		if (unlikely(dma_mapping_error(netcp->dev, dma)))
 			goto fail;
 
-		pad[0] = lower_32_bits((uintptr_t)bufptr);
-		pad[1] = upper_32_bits((uintptr_t)bufptr);
-
+		pad[0] = (u32)bufptr;
 	} else {
 		/* Allocate a secondary receive queue entry */
 		page = alloc_page(GFP_ATOMIC | GFP_DMA | __GFP_COLD);

@@ -870,9 +852,8 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 		}
 		buf_len = PAGE_SIZE;
 		dma = dma_map_page(netcp->dev, page, 0, buf_len, DMA_TO_DEVICE);
-		pad[0] = lower_32_bits(dma);
-		pad[1] = upper_32_bits(dma);
-		pad[2] = 0;
+		pad[0] = (u32)page;
+		pad[1] = 0;
 	}
 
 	desc_info =  KNAV_DMA_DESC_PS_INFO_IN_DESC;

@@ -882,7 +863,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 	pkt_info |= (netcp->rx_queue_id & KNAV_DMA_DESC_RETQ_MASK) <<
 		    KNAV_DMA_DESC_RETQ_SHIFT;
 	set_org_pkt_info(dma, buf_len, hwdesc);
-	set_pad_info(pad[0], pad[1], pad[2], hwdesc);
+	set_pad_info(pad[0], pad[1], hwdesc);
 	set_desc_info(desc_info, pkt_info, hwdesc);
 
 	/* Push to FDQs */

@@ -971,11 +952,11 @@ static int netcp_process_tx_compl_packets(struct netcp_intf *netcp,
 					  unsigned int budget)
 {
 	struct knav_dma_desc *desc;
-	void *ptr;
 	struct sk_buff *skb;
 	unsigned int dma_sz;
 	dma_addr_t dma;
 	int pkts = 0;
+	u32 tmp;
 
 	while (budget--) {
 		dma = knav_queue_pop(netcp->tx_compl_q, &dma_sz);

@@ -988,8 +969,7 @@ static int netcp_process_tx_compl_packets(struct netcp_intf *netcp,
 			continue;
 		}
 
-		get_pad_ptr(&ptr, desc);
-		skb = ptr;
+		get_pad_info((u32 *)&skb, &tmp, desc);
 		netcp_free_tx_desc_chain(netcp, desc, dma_sz);
 		if (!skb) {
 			dev_err(netcp->ndev_dev, "No skb in Tx desc\n");

@@ -1194,10 +1174,7 @@ static int netcp_tx_submit_skb(struct netcp_intf *netcp,
 	}
 
 	set_words(&tmp, 1, &desc->packet_info);
-	tmp = lower_32_bits((uintptr_t)&skb);
-	set_words(&tmp, 1, &desc->pad[0]);
-	tmp = upper_32_bits((uintptr_t)&skb);
-	set_words(&tmp, 1, &desc->pad[1]);
+	set_words((u32 *)&skb, 1, &desc->pad[0]);
 
 	if (tx_pipe->flags & SWITCH_TO_PORT_IN_TAGINFO) {
 		tmp = tx_pipe->switch_to_port;

-- 
1.9.1

Rename the pad to sw_data as per description of this field in the hardware
spec(refer sprugr9 from www.ti.com). Latest version of the document is
at http://www.ti.com/lit/ug/sprugr9h/sprugr9h.pdf and section 3.1
Host Packet Descriptor describes this field.

Also define and use a constant for the size of sw_data field similar to
other fields in the struct for desc and document the sw_data field
in the header. As the sw_data is not touched by hw, it's type can be
changed to u32.

Cc: Wingman Kwok <redacted>
Cc: Mugunthan V N <redacted>
CC: Arnd Bergmann <arnd@arndb.de>
CC: Grygorii Strashko <grygorii.strashko@ti.com>
CC: David Laight <redacted>
Signed-off-by: Murali Karicheri <redacted>
---
 new patch based on discussion at https://patchwork.ozlabs.org/patch/580860/
 include/linux/soc/ti/knav_dma.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/soc/ti/knav_dma.h b/include/linux/soc/ti/knav_dma.h
index 343c13a..35cb926 100644
--- a/include/linux/soc/ti/knav_dma.h
+++ b/include/linux/soc/ti/knav_dma.h

@@ -44,6 +44,7 @@
 
 #define KNAV_DMA_NUM_EPIB_WORDS			4
 #define KNAV_DMA_NUM_PS_WORDS			16
+#define KNAV_DMA_NUM_SW_DATA_WORDS		4
 #define KNAV_DMA_FDQ_PER_CHAN			4
 
 /* Tx channel scheduling priority */

@@ -142,6 +143,7 @@ struct knav_dma_cfg {
  * @orig_buff:			buff pointer since 'buff' can be overwritten
  * @epib:			Extended packet info block
  * @psdata:			Protocol specific
+ * @sw_data:			Software private data not touched by h/w
  */
 struct knav_dma_desc {
 	__le32	desc_info;

@@ -154,7 +156,7 @@ struct knav_dma_desc {
 	__le32	orig_buff;
 	__le32	epib[KNAV_DMA_NUM_EPIB_WORDS];
 	__le32	psdata[KNAV_DMA_NUM_PS_WORDS];
-	__le32	pad[4];
+	u32	sw_data[KNAV_DMA_NUM_SW_DATA_WORDS];
 } ____cacheline_aligned;
 
 #if IS_ENABLED(CONFIG_KEYSTONE_NAVIGATOR_DMA)

-- 
1.9.1

Rename the helpers to match with the updated dma desc field sw_data.

Cc: Wingman Kwok <redacted>
Cc: Mugunthan V N <redacted>
CC: Arnd Bergmann <arnd@arndb.de>
CC: Grygorii Strashko <grygorii.strashko@ti.com>
CC: David Laight <redacted>
Signed-off-by: Murali Karicheri <redacted>
---
 v1 - new patch to based on discussion at
	https://patchwork.ozlabs.org/patch/580860/
 drivers/net/ethernet/ti/netcp_core.c | 40 +++++++++++++++++++-----------------
 1 file changed, 21 insertions(+), 19 deletions(-)

diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c
index 0b26e52..1d07cca 100644
--- a/drivers/net/ethernet/ti/netcp_core.c
+++ b/drivers/net/ethernet/ti/netcp_core.c

@@ -117,10 +117,11 @@ static void get_pkt_info(dma_addr_t *buff, u32 *buff_len, dma_addr_t *ndesc,
 	*ndesc = le32_to_cpu(desc->next_desc);
 }
 
-static void get_pad_info(u32 *pad0, u32 *pad1, struct knav_dma_desc *desc)
+static void get_sw_data(u32 *data0, u32 *data1, struct knav_dma_desc *desc)
 {
-	*pad0 = le32_to_cpu(desc->pad[0]);
-	*pad1 = le32_to_cpu(desc->pad[1]);
+	/* No Endian conversion needed as this data is untouched by hw */
+	*data0 = desc->sw_data[0];
+	*data1 = desc->sw_data[1];
 }
 
 static void get_org_pkt_info(dma_addr_t *buff, u32 *buff_len,

@@ -153,10 +154,11 @@ static void set_desc_info(u32 desc_info, u32 pkt_info,
 	desc->packet_info = cpu_to_le32(pkt_info);
 }
 
-static void set_pad_info(u32 pad0, u32 pad1, struct knav_dma_desc *desc)
+static void set_sw_data(u32 data0, u32 data1, struct knav_dma_desc *desc)
 {
-	desc->pad[0] = cpu_to_le32(pad0);
-	desc->pad[1] = cpu_to_le32(pad1);
+	/* No Endian conversion needed as this data is untouched by hw */
+	desc->sw_data[0] = data0;
+	desc->sw_data[1] = data1;
 }
 
 static void set_org_pkt_info(dma_addr_t buff, u32 buff_len,

@@ -581,12 +583,12 @@ static void netcp_free_rx_desc_chain(struct netcp_intf *netcp,
 			break;
 		}
 		get_pkt_info(&dma_buf, &tmp, &dma_desc, ndesc);
-		get_pad_info((u32 *)&buf_ptr, &buf_len, ndesc);
+		get_sw_data((u32 *)&buf_ptr, &buf_len, ndesc);
 		dma_unmap_page(netcp->dev, dma_buf, PAGE_SIZE, DMA_FROM_DEVICE);
 		__free_page(buf_ptr);
 		knav_pool_desc_put(netcp->rx_pool, desc);
 	}
-	get_pad_info((u32 *)&buf_ptr, &buf_len, desc);
+	get_sw_data((u32 *)&buf_ptr, &buf_len, desc);
 
 	if (buf_ptr)
 		netcp_frag_free(buf_len <= PAGE_SIZE, buf_ptr);

@@ -639,7 +641,7 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 	}
 
 	get_pkt_info(&dma_buff, &buf_len, &dma_desc, desc);
-	get_pad_info((u32 *)&org_buf_ptr, &org_buf_len, desc);
+	get_sw_data((u32 *)&org_buf_ptr, &org_buf_len, desc);
 
 	if (unlikely(!org_buf_ptr)) {
 		dev_err(netcp->ndev_dev, "NULL bufptr in desc\n");

@@ -672,7 +674,7 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 		}
 
 		get_pkt_info(&dma_buff, &buf_len, &dma_desc, ndesc);
-		get_pad_info((u32 *)&page, &tmp, ndesc);
+		get_sw_data((u32 *)&page, &tmp, ndesc);
 
 		if (likely(dma_buff && buf_len && page)) {
 			dma_unmap_page(netcp->dev, dma_buff, PAGE_SIZE,

@@ -761,7 +763,7 @@ static void netcp_free_rx_buf(struct netcp_intf *netcp, int fdq)
 		}
 
 		get_org_pkt_info(&dma, &buf_len, desc);
-		get_pad_info((u32 *)&buf_ptr, &tmp, desc);
+		get_sw_data((u32 *)&buf_ptr, &tmp, desc);
 
 		if (unlikely(!dma)) {
 			dev_err(netcp->ndev_dev, "NULL orig_buff in desc\n");

@@ -813,7 +815,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 	struct page *page;
 	dma_addr_t dma;
 	void *bufptr;
-	u32 pad[2];
+	u32 sw_data[2];
 
 	/* Allocate descriptor */
 	hwdesc = knav_pool_desc_get(netcp->rx_pool);

@@ -830,7 +832,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 				SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 
 		bufptr = netdev_alloc_frag(primary_buf_len);
-		pad[1] = primary_buf_len;
+		sw_data[1] = primary_buf_len;
 
 		if (unlikely(!bufptr)) {
 			dev_warn_ratelimited(netcp->ndev_dev,

@@ -842,7 +844,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 		if (unlikely(dma_mapping_error(netcp->dev, dma)))
 			goto fail;
 
-		pad[0] = (u32)bufptr;
+		sw_data[0] = (u32)bufptr;
 	} else {
 		/* Allocate a secondary receive queue entry */
 		page = alloc_page(GFP_ATOMIC | GFP_DMA | __GFP_COLD);

@@ -852,8 +854,8 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 		}
 		buf_len = PAGE_SIZE;
 		dma = dma_map_page(netcp->dev, page, 0, buf_len, DMA_TO_DEVICE);
-		pad[0] = (u32)page;
-		pad[1] = 0;
+		sw_data[0] = (u32)page;
+		sw_data[1] = 0;
 	}
 
 	desc_info =  KNAV_DMA_DESC_PS_INFO_IN_DESC;

@@ -863,7 +865,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 	pkt_info |= (netcp->rx_queue_id & KNAV_DMA_DESC_RETQ_MASK) <<
 		    KNAV_DMA_DESC_RETQ_SHIFT;
 	set_org_pkt_info(dma, buf_len, hwdesc);
-	set_pad_info(pad[0], pad[1], hwdesc);
+	set_sw_data(sw_data[0], sw_data[1], hwdesc);
 	set_desc_info(desc_info, pkt_info, hwdesc);
 
 	/* Push to FDQs */

@@ -969,7 +971,7 @@ static int netcp_process_tx_compl_packets(struct netcp_intf *netcp,
 			continue;
 		}
 
-		get_pad_info((u32 *)&skb, &tmp, desc);
+		get_sw_data((u32 *)&skb, &tmp, desc);
 		netcp_free_tx_desc_chain(netcp, desc, dma_sz);
 		if (!skb) {
 			dev_err(netcp->ndev_dev, "No skb in Tx desc\n");

@@ -1174,7 +1176,7 @@ static int netcp_tx_submit_skb(struct netcp_intf *netcp,
 	}
 
 	set_words(&tmp, 1, &desc->packet_info);
-	set_words((u32 *)&skb, 1, &desc->pad[0]);
+	set_words((u32 *)&skb, 1, &desc->sw_data[0]);
 
 	if (tx_pipe->flags & SWITCH_TO_PORT_IN_TAGINFO) {
 		tmp = tx_pipe->switch_to_port;

-- 
1.9.1

SW data field in descriptor can be used by software to hold private
data for the driver. As there are 4 words available for this purpose,
use separate macros to place it or retrieve the same to/from
descriptors. Also do type cast of data types accordingly.

Cc: Wingman Kwok <redacted>
Cc: Mugunthan V N <redacted>
CC: Arnd Bergmann <arnd@arndb.de>
CC: Grygorii Strashko <grygorii.strashko@ti.com>
CC: David Laight <redacted>
Signed-off-by: Murali Karicheri <redacted>
---
 v1 - new patch based on discussion at
      https://patchwork.ozlabs.org/patch/580860/
 drivers/net/ethernet/ti/netcp_core.c | 43 ++++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 16 deletions(-)

diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c
index 1d07cca..8b353e4 100644
--- a/drivers/net/ethernet/ti/netcp_core.c
+++ b/drivers/net/ethernet/ti/netcp_core.c

@@ -117,13 +117,18 @@ static void get_pkt_info(dma_addr_t *buff, u32 *buff_len, dma_addr_t *ndesc,
 	*ndesc = le32_to_cpu(desc->next_desc);
 }
 
-static void get_sw_data(u32 *data0, u32 *data1, struct knav_dma_desc *desc)
+static u32 get_sw_data(int index, struct knav_dma_desc *desc)
 {
 	/* No Endian conversion needed as this data is untouched by hw */
-	*data0 = desc->sw_data[0];
-	*data1 = desc->sw_data[1];
+	return desc->sw_data[index];
 }
 
+/* use these macros to get sw data */
+#define GET_SW_DATA0(desc) get_sw_data(0, desc)
+#define GET_SW_DATA1(desc) get_sw_data(1, desc)
+#define GET_SW_DATA2(desc) get_sw_data(2, desc)
+#define GET_SW_DATA3(desc) get_sw_data(3, desc)
+
 static void get_org_pkt_info(dma_addr_t *buff, u32 *buff_len,
 			     struct knav_dma_desc *desc)
 {

@@ -154,13 +159,18 @@ static void set_desc_info(u32 desc_info, u32 pkt_info,
 	desc->packet_info = cpu_to_le32(pkt_info);
 }
 
-static void set_sw_data(u32 data0, u32 data1, struct knav_dma_desc *desc)
+static void set_sw_data(int index, u32 data, struct knav_dma_desc *desc)
 {
 	/* No Endian conversion needed as this data is untouched by hw */
-	desc->sw_data[0] = data0;
-	desc->sw_data[1] = data1;
+	desc->sw_data[index] = data;
 }
 
+/* use these macros to set sw data */
+#define SET_SW_DATA0(data, desc) set_sw_data(0, data, desc)
+#define SET_SW_DATA1(data, desc) set_sw_data(1, data, desc)
+#define SET_SW_DATA2(data, desc) set_sw_data(2, data, desc)
+#define SET_SW_DATA3(data, desc) set_sw_data(3, data, desc)
+
 static void set_org_pkt_info(dma_addr_t buff, u32 buff_len,
 			     struct knav_dma_desc *desc)
 {

@@ -583,12 +593,14 @@ static void netcp_free_rx_desc_chain(struct netcp_intf *netcp,
 			break;
 		}
 		get_pkt_info(&dma_buf, &tmp, &dma_desc, ndesc);
-		get_sw_data((u32 *)&buf_ptr, &buf_len, ndesc);
+		buf_ptr = (void *)GET_SW_DATA0(ndesc);
+		buf_len = (int)GET_SW_DATA1(desc);
 		dma_unmap_page(netcp->dev, dma_buf, PAGE_SIZE, DMA_FROM_DEVICE);
 		__free_page(buf_ptr);
 		knav_pool_desc_put(netcp->rx_pool, desc);
 	}
-	get_sw_data((u32 *)&buf_ptr, &buf_len, desc);
+	buf_ptr = (void *)GET_SW_DATA0(desc);
+	buf_len = (int)GET_SW_DATA1(desc);
 
 	if (buf_ptr)
 		netcp_frag_free(buf_len <= PAGE_SIZE, buf_ptr);

@@ -628,7 +640,6 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 	struct netcp_packet p_info;
 	struct sk_buff *skb;
 	void *org_buf_ptr;
-	u32 tmp;
 
 	dma_desc = knav_queue_pop(netcp->rx_queue, &dma_sz);
 	if (!dma_desc)

@@ -641,7 +652,8 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 	}
 
 	get_pkt_info(&dma_buff, &buf_len, &dma_desc, desc);
-	get_sw_data((u32 *)&org_buf_ptr, &org_buf_len, desc);
+	org_buf_ptr = (void *)GET_SW_DATA0(desc);
+	org_buf_len = (int)GET_SW_DATA1(desc);
 
 	if (unlikely(!org_buf_ptr)) {
 		dev_err(netcp->ndev_dev, "NULL bufptr in desc\n");

@@ -674,7 +686,7 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 		}
 
 		get_pkt_info(&dma_buff, &buf_len, &dma_desc, ndesc);
-		get_sw_data((u32 *)&page, &tmp, ndesc);
+		page = (struct page *)GET_SW_DATA0(desc);
 
 		if (likely(dma_buff && buf_len && page)) {
 			dma_unmap_page(netcp->dev, dma_buff, PAGE_SIZE,

@@ -752,7 +764,6 @@ static void netcp_free_rx_buf(struct netcp_intf *netcp, int fdq)
 	unsigned int buf_len, dma_sz;
 	dma_addr_t dma;
 	void *buf_ptr;
-	u32 tmp;
 
 	/* Allocate descriptor */
 	while ((dma = knav_queue_pop(netcp->rx_fdq[fdq], &dma_sz))) {

@@ -763,7 +774,7 @@ static void netcp_free_rx_buf(struct netcp_intf *netcp, int fdq)
 		}
 
 		get_org_pkt_info(&dma, &buf_len, desc);
-		get_sw_data((u32 *)&buf_ptr, &tmp, desc);
+		buf_ptr = (void *)GET_SW_DATA0(desc);
 
 		if (unlikely(!dma)) {
 			dev_err(netcp->ndev_dev, "NULL orig_buff in desc\n");

@@ -865,7 +876,8 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 	pkt_info |= (netcp->rx_queue_id & KNAV_DMA_DESC_RETQ_MASK) <<
 		    KNAV_DMA_DESC_RETQ_SHIFT;
 	set_org_pkt_info(dma, buf_len, hwdesc);
-	set_sw_data(sw_data[0], sw_data[1], hwdesc);
+	SET_SW_DATA0(sw_data[0], hwdesc);
+	SET_SW_DATA1(sw_data[1], hwdesc);
 	set_desc_info(desc_info, pkt_info, hwdesc);
 
 	/* Push to FDQs */

@@ -958,7 +970,6 @@ static int netcp_process_tx_compl_packets(struct netcp_intf *netcp,
 	unsigned int dma_sz;
 	dma_addr_t dma;
 	int pkts = 0;
-	u32 tmp;
 
 	while (budget--) {
 		dma = knav_queue_pop(netcp->tx_compl_q, &dma_sz);

@@ -971,7 +982,7 @@ static int netcp_process_tx_compl_packets(struct netcp_intf *netcp,
 			continue;
 		}
 
-		get_sw_data((u32 *)&skb, &tmp, desc);
+		skb = (struct sk_buff *)GET_SW_DATA0(desc);
 		netcp_free_tx_desc_chain(netcp, desc, dma_sz);
 		if (!skb) {
 			dev_err(netcp->ndev_dev, "No skb in Tx desc\n");

-- 
1.9.1

On Thursday 18 February 2016 14:46:15 Murali Karicheri wrote:

Rename the pad to sw_data as per description of this field in the hardware
spec(refer sprugr9 from www.ti.com). Latest version of the document is
at http://www.ti.com/lit/ug/sprugr9h/sprugr9h.pdf and section 3.1
Host Packet Descriptor describes this field.

Also define and use a constant for the size of sw_data field similar to
other fields in the struct for desc and document the sw_data field
in the header. As the sw_data is not touched by hw, it's type can be
changed to u32.

Acked-by: Arnd Bergmann <arnd@arndb.de>

On Thursday 18 February 2016 14:46:16 Murali Karicheri wrote:

Actually this needs to be done together with patch 2, or you
get a build failure if this one is not yet applied.

This seems to introduce a bug, and should produce an "sparse" warning
about a u32 being passed into a function expecting a __le32.

The other bug I originally tried to address here is the way an indirect
pointer is converted to a 'u32' pointer, which won't work on 64-bit
architectures when pointers are wider than u32. Maybe at least put a
comment here that this is a known deficiency.

	Arnd

On Thursday 18 February 2016 14:46:14 Murali Karicheri wrote:

From: Arnd Bergmann <arnd@arndb.de>

The commit 899077791403 ("netcp: try to reduce type confusion in
descriptors") introduces a regression in Kernel 4.5-rc1 and it breaks
get/set_pad_info() functionality.

The TI NETCP driver uses pad0 and pad1 fields of knav_dma_desc to
store DMA/MEM buffer pointer and buffer size respectively. And in both
cases for Keystone 2 the pointer type size is 32 bit regardless of
LAPE enabled or not, because CONFIG_ARCH_DMA_ADDR_T_64BIT originally
is not expected to be defined.

			!LAPE	LPAE
sizeof(void*)		32bit	32bit
sizeof(dma_addr_t) 	32bit	32bit
sizeof(phys_addr_t) 	32bit	64bit

As this was never relevant or true, I don't think it needs to be
mentioned here, it just confuses things. Please just assume that
dma_addr_t can be 64-bit wide, but will only contain 32-bit
numbers on keystone.

Unfortunately, above commit changed buffer's pointers save/restore
code (get/set_pad_info()) and added intermediate conversation to u64
which works incorrectly on 32bit Keystone 2 and causes TI NETCP driver
crash in RX/TX path due to "Unable to handle kernel NULL pointer"
exception. This issue was reported and discussed in [1].

Have you been able to figure out why it actually broke? I'd still
like to know.

Hence, fix it by partially reverting above commit and restoring
get/set_pad_info() functionality as it was before.

[1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95361.html
Cc: Wingman Kwok <redacted>
Cc: Mugunthan V N <redacted>
CC: David Laight <redacted>
Reported-by: Franklin S Cooper Jr <redacted>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Murali Karicheri <redacted>

I don't think I sent this patch with a 'Signed-off-by', did I?
(I could be misremembering that).

	Arnd

On 02/19/2016 09:41 AM, Arnd Bergmann wrote:

On Thursday 18 February 2016 14:46:14 Murali Karicheri wrote:

quoted

From: Arnd Bergmann <arnd@arndb.de>

The commit 899077791403 ("netcp: try to reduce type confusion in
descriptors") introduces a regression in Kernel 4.5-rc1 and it breaks
get/set_pad_info() functionality.

The TI NETCP driver uses pad0 and pad1 fields of knav_dma_desc to
store DMA/MEM buffer pointer and buffer size respectively. And in both
cases for Keystone 2 the pointer type size is 32 bit regardless of
LAPE enabled or not, because CONFIG_ARCH_DMA_ADDR_T_64BIT originally
is not expected to be defined.

			!LAPE	LPAE
sizeof(void*)		32bit	32bit
sizeof(dma_addr_t) 	32bit	32bit
sizeof(phys_addr_t) 	32bit	64bit

As this was never relevant or true, I don't think it needs to be
mentioned here, it just confuses things. Please just assume that
dma_addr_t can be 64-bit wide, but will only contain 32-bit
numbers on keystone.

I can remove this from the commit description and re-send.

quoted

Unfortunately, above commit changed buffer's pointers save/restore
code (get/set_pad_info()) and added intermediate conversation to u64
which works incorrectly on 32bit Keystone 2 and causes TI NETCP driver
crash in RX/TX path due to "Unable to handle kernel NULL pointer"
exception. This issue was reported and discussed in [1].

Have you been able to figure out why it actually broke? I'd still
like to know.

As Grygorii is out of office until Monday, I would like to step in.
I will take some time today to try review the reverted changes for
failure reason and get back. But as you have agreed in the discussion
at https://www.mail-archive.com/netdev@vger.kernel.org/msg96311.html
Can we fix the regression by applying this patch and rest of the series
if it looks good? If I need to separate this from rest of the series,
let me know and I can take care of that.

quoted

Hence, fix it by partially reverting above commit and restoring
get/set_pad_info() functionality as it was before.

[1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95361.html
Cc: Wingman Kwok <redacted>
Cc: Mugunthan V N <redacted>
CC: David Laight <redacted>
Reported-by: Franklin S Cooper Jr <redacted>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Murali Karicheri <redacted>

I don't think I sent this patch with a 'Signed-off-by', did I?
(I could be misremembering that).

I think you had agreed based on what I read at
https://www.mail-archive.com/netdev@vger.kernel.org/msg96311.html

reproduced below for your convenience.
=============================================================================

What I could do now is update your/my patch as i mentioned in [1]
and re-send it at the weekend (with your authorship and my signoff).
Do you agree?


[1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95831.html

Yes, let's do that in the meantime. I can also make sure that that
the driver doesn't build on 64-bit, just in case.
=============================================================================

Hope I can keep your sign-off when I re-send this. Please confirm.

Murali

	Arnd

-- 
Murali Karicheri
Linux Kernel, Keystone

On Friday 19 February 2016 10:48:30 Murali Karicheri wrote:

On 02/19/2016 09:41 AM, Arnd Bergmann wrote:

quoted

On Thursday 18 February 2016 14:46:14 Murali Karicheri wrote:

quoted

From: Arnd Bergmann <arnd@arndb.de>

The commit 899077791403 ("netcp: try to reduce type confusion in
descriptors") introduces a regression in Kernel 4.5-rc1 and it breaks
get/set_pad_info() functionality.

The TI NETCP driver uses pad0 and pad1 fields of knav_dma_desc to
store DMA/MEM buffer pointer and buffer size respectively. And in both
cases for Keystone 2 the pointer type size is 32 bit regardless of
LAPE enabled or not, because CONFIG_ARCH_DMA_ADDR_T_64BIT originally
is not expected to be defined.

                     !LAPE   LPAE
sizeof(void*)                32bit   32bit
sizeof(dma_addr_t)   32bit   32bit
sizeof(phys_addr_t)  32bit   64bit

As this was never relevant or true, I don't think it needs to be
mentioned here, it just confuses things. Please just assume that
dma_addr_t can be 64-bit wide, but will only contain 32-bit
numbers on keystone.

I can remove this from the commit description and re-send.

Ok

quoted

quoted

Unfortunately, above commit changed buffer's pointers save/restore
code (get/set_pad_info()) and added intermediate conversation to u64
which works incorrectly on 32bit Keystone 2 and causes TI NETCP driver
crash in RX/TX path due to "Unable to handle kernel NULL pointer"
exception. This issue was reported and discussed in [1].

Have you been able to figure out why it actually broke? I'd still
like to know.

As Grygorii is out of office until Monday, I would like to step in.
I will take some time today to try review the reverted changes for
failure reason and get back. But as you have agreed in the discussion
at https://www.mail-archive.com/netdev@vger.kernel.org/msg96311.html
Can we fix the regression by applying this patch and rest of the series
if it looks good? If I need to separate this from rest of the series,
let me know and I can take care of that.

Yes, sounds fine.

quoted

quoted

Hence, fix it by partially reverting above commit and restoring
get/set_pad_info() functionality as it was before.

[1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95361.html
Cc: Wingman Kwok <redacted>
Cc: Mugunthan V N <redacted>
CC: David Laight <redacted>
Reported-by: Franklin S Cooper Jr <redacted>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Murali Karicheri <redacted>

I don't think I sent this patch with a 'Signed-off-by', did I?
(I could be misremembering that).

I think you had agreed based on what I read at
https://www.mail-archive.com/netdev@vger.kernel.org/msg96311.html

reproduced below for your convenience.
=============================================================================

quoted

What I could do now is update your/my patch as i mentioned in [1]
and re-send it at the weekend (with your authorship and my signoff).
Do you agree?


[1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95831.html

Yes, let's do that in the meantime. I can also make sure that that
the driver doesn't build on 64-bit, just in case.
=============================================================================

Hope I can keep your sign-off when I re-send this. Please confirm.

The most important part here is that you don't add a "Signed-off-by"
tag unless it was provided by that person as part of the submission.

I'm slightly uncomfortable with having my Signed-off-by as the first
one when I did not write the changelog myself, so I'd prefer if
you just add my Acked-by once I provide that. If that doesn't
work for you, let's follow up in private to sort it out.

	Arnd

On 02/19/2016 11:41 AM, Arnd Bergmann wrote:

On Friday 19 February 2016 10:48:30 Murali Karicheri wrote:

quoted

On 02/19/2016 09:41 AM, Arnd Bergmann wrote:

quoted

On Thursday 18 February 2016 14:46:14 Murali Karicheri wrote:

quoted

From: Arnd Bergmann <arnd@arndb.de>

The commit 899077791403 ("netcp: try to reduce type confusion in
descriptors") introduces a regression in Kernel 4.5-rc1 and it breaks
get/set_pad_info() functionality.

The TI NETCP driver uses pad0 and pad1 fields of knav_dma_desc to
store DMA/MEM buffer pointer and buffer size respectively. And in both
cases for Keystone 2 the pointer type size is 32 bit regardless of
LAPE enabled or not, because CONFIG_ARCH_DMA_ADDR_T_64BIT originally
is not expected to be defined.

                     !LAPE   LPAE
sizeof(void*)                32bit   32bit
sizeof(dma_addr_t)   32bit   32bit
sizeof(phys_addr_t)  32bit   64bit

As this was never relevant or true, I don't think it needs to be
mentioned here, it just confuses things. Please just assume that
dma_addr_t can be 64-bit wide, but will only contain 32-bit
numbers on keystone.

I can remove this from the commit description and re-send.

Ok

quoted

quoted

quoted

Unfortunately, above commit changed buffer's pointers save/restore
code (get/set_pad_info()) and added intermediate conversation to u64
which works incorrectly on 32bit Keystone 2 and causes TI NETCP driver
crash in RX/TX path due to "Unable to handle kernel NULL pointer"
exception. This issue was reported and discussed in [1].

Have you been able to figure out why it actually broke? I'd still
like to know.

As Grygorii is out of office until Monday, I would like to step in.
I will take some time today to try review the reverted changes for
failure reason and get back. But as you have agreed in the discussion
at https://www.mail-archive.com/netdev@vger.kernel.org/msg96311.html
Can we fix the regression by applying this patch and rest of the series
if it looks good? If I need to separate this from rest of the series,
let me know and I can take care of that.

Yes, sounds fine.

quoted

quoted

quoted

Hence, fix it by partially reverting above commit and restoring
get/set_pad_info() functionality as it was before.

[1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95361.html
Cc: Wingman Kwok <redacted>
Cc: Mugunthan V N <redacted>
CC: David Laight <redacted>
Reported-by: Franklin S Cooper Jr <redacted>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Murali Karicheri <redacted>

I don't think I sent this patch with a 'Signed-off-by', did I?
(I could be misremembering that).

I think you had agreed based on what I read at
https://www.mail-archive.com/netdev@vger.kernel.org/msg96311.html

reproduced below for your convenience.
=============================================================================

quoted

What I could do now is update your/my patch as i mentioned in [1]
and re-send it at the weekend (with your authorship and my signoff).
Do you agree?


[1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95831.html

Yes, let's do that in the meantime. I can also make sure that that
the driver doesn't build on 64-bit, just in case.
=============================================================================

Hope I can keep your sign-off when I re-send this. Please confirm.

The most important part here is that you don't add a "Signed-off-by"
tag unless it was provided by that person as part of the submission.

I'm slightly uncomfortable with having my Signed-off-by as the first
one when I did not write the changelog myself, so I'd prefer if
you just add my Acked-by once I provide that. If that doesn't
work for you, let's follow up in private to sort it out.

Ok. I will remove it.

	Arnd

-- 
Murali Karicheri
Linux Kernel, Keystone

On 02/19/2016 09:37 AM, Arnd Bergmann wrote:

On Thursday 18 February 2016 14:46:16 Murali Karicheri wrote:

quoted

Rename the helpers to match with the updated dma desc field sw_data.

Cc: Wingman Kwok <redacted>
Cc: Mugunthan V N <redacted>
CC: Arnd Bergmann <arnd@arndb.de>
CC: Grygorii Strashko <grygorii.strashko@ti.com>
CC: David Laight <redacted>
Signed-off-by: Murali Karicheri <redacted>
---
 v1 - new patch to based on discussion at
	https://patchwork.ozlabs.org/patch/580860/
 drivers/net/ethernet/ti/netcp_core.c | 40 +++++++++++++++++++-----------------
 1 file changed, 21 insertions(+), 19 deletions(-)

diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c
index 0b26e52..1d07cca 100644
--- a/drivers/net/ethernet/ti/netcp_core.c
+++ b/drivers/net/ethernet/ti/netcp_core.c

@@ -117,10 +117,11 @@ static void get_pkt_info(dma_addr_t *buff, u32 *buff_len, dma_addr_t *ndesc,
 	*ndesc = le32_to_cpu(desc->next_desc);
 }
 
-static void get_pad_info(u32 *pad0, u32 *pad1, struct knav_dma_desc *desc)
+static void get_sw_data(u32 *data0, u32 *data1, struct knav_dma_desc *desc)
 {
-	*pad0 = le32_to_cpu(desc->pad[0]);
-	*pad1 = le32_to_cpu(desc->pad[1]);
+	/* No Endian conversion needed as this data is untouched by hw */
+	*data0 = desc->sw_data[0];
+	*data1 = desc->sw_data[1];
 }

Actually this needs to be done together with patch 2, or you
get a build failure if this one is not yet applied.

I have realized that. Only reason was that it belongs to drivers/soc which is
merged through Santosh. I will combine it and re-send.

quoted

@@ -1174,7 +1176,7 @@ static int netcp_tx_submit_skb(struct netcp_intf *netcp,
 	}
 
 	set_words(&tmp, 1, &desc->packet_info);
-	set_words((u32 *)&skb, 1, &desc->pad[0]);
+	set_words((u32 *)&skb, 1, &desc->sw_data[0]);
 
 	if (tx_pipe->flags & SWITCH_TO_PORT_IN_TAGINFO) {
 		tmp = tx_pipe->switch_to_port;

This seems to introduce a bug, and should produce an "sparse" warning
about a u32 being passed into a function expecting a __le32.

Ahah, this was changed recently. I will take a look.

The other bug I originally tried to address here is the way an indirect
pointer is converted to a 'u32' pointer, which won't work on 64-bit
architectures when pointers are wider than u32. Maybe at least put a
comment here that this is a known deficiency.

Ok. Let me check and respond.

	Arnd

-- 
Murali Karicheri
Linux Kernel, Keystone

On 02/19/2016 09:37 AM, Arnd Bergmann wrote:

On Thursday 18 February 2016 14:46:16 Murali Karicheri wrote:

quoted

Rename the helpers to match with the updated dma desc field sw_data.

Cc: Wingman Kwok <redacted>
Cc: Mugunthan V N <redacted>
CC: Arnd Bergmann <arnd@arndb.de>
CC: Grygorii Strashko <grygorii.strashko@ti.com>
CC: David Laight <redacted>
Signed-off-by: Murali Karicheri <redacted>
---
 v1 - new patch to based on discussion at
	https://patchwork.ozlabs.org/patch/580860/
 drivers/net/ethernet/ti/netcp_core.c | 40 +++++++++++++++++++-----------------
 1 file changed, 21 insertions(+), 19 deletions(-)

diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c
index 0b26e52..1d07cca 100644
--- a/drivers/net/ethernet/ti/netcp_core.c
+++ b/drivers/net/ethernet/ti/netcp_core.c

@@ -117,10 +117,11 @@ static void get_pkt_info(dma_addr_t *buff, u32 *buff_len, dma_addr_t *ndesc,
 	*ndesc = le32_to_cpu(desc->next_desc);
 }
 
-static void get_pad_info(u32 *pad0, u32 *pad1, struct knav_dma_desc *desc)
+static void get_sw_data(u32 *data0, u32 *data1, struct knav_dma_desc *desc)
 {
-	*pad0 = le32_to_cpu(desc->pad[0]);
-	*pad1 = le32_to_cpu(desc->pad[1]);
+	/* No Endian conversion needed as this data is untouched by hw */
+	*data0 = desc->sw_data[0];
+	*data1 = desc->sw_data[1];
 }

Actually this needs to be done together with patch 2, or you
get a build failure if this one is not yet applied.

quoted

@@ -1174,7 +1176,7 @@ static int netcp_tx_submit_skb(struct netcp_intf *netcp,
 	}
 
 	set_words(&tmp, 1, &desc->packet_info);
-	set_words((u32 *)&skb, 1, &desc->pad[0]);
+	set_words((u32 *)&skb, 1, &desc->sw_data[0]);
 
 	if (tx_pipe->flags & SWITCH_TO_PORT_IN_TAGINFO) {
 		tmp = tx_pipe->switch_to_port;

This seems to introduce a bug, and should produce an "sparse" warning
about a u32 being passed into a function expecting a __le32.

The fix is to use set_sw_data() instead. I could reproduce the sparse
warning you mentioned and fixed using the above. Will be part of v2.

The other bug I originally tried to address here is the way an indirect
pointer is converted to a 'u32' pointer, which won't work on 64-bit
architectures when pointers are wider than u32. Maybe at least put a
comment here that this is a known deficiency.

Will add a comment here and other possible places we do similar things as
much as I can.

Murali

	Arnd

-- 
Murali Karicheri
Linux Kernel, Keystone

On 02/19/2016 09:41 AM, Arnd Bergmann wrote:

On Thursday 18 February 2016 14:46:14 Murali Karicheri wrote:

quoted

From: Arnd Bergmann <arnd@arndb.de>

The commit 899077791403 ("netcp: try to reduce type confusion in
descriptors") introduces a regression in Kernel 4.5-rc1 and it breaks
get/set_pad_info() functionality.

The TI NETCP driver uses pad0 and pad1 fields of knav_dma_desc to
store DMA/MEM buffer pointer and buffer size respectively. And in both
cases for Keystone 2 the pointer type size is 32 bit regardless of
LAPE enabled or not, because CONFIG_ARCH_DMA_ADDR_T_64BIT originally
is not expected to be defined.

			!LAPE	LPAE
sizeof(void*)		32bit	32bit
sizeof(dma_addr_t) 	32bit	32bit
sizeof(phys_addr_t) 	32bit	64bit

As this was never relevant or true, I don't think it needs to be
mentioned here, it just confuses things. Please just assume that
dma_addr_t can be 64-bit wide, but will only contain 32-bit
numbers on keystone.

quoted

Unfortunately, above commit changed buffer's pointers save/restore
code (get/set_pad_info()) and added intermediate conversation to u64
which works incorrectly on 32bit Keystone 2 and causes TI NETCP driver
crash in RX/TX path due to "Unable to handle kernel NULL pointer"
exception. This issue was reported and discussed in [1].

Have you been able to figure out why it actually broke? I'd still
like to know.

I have just send v2. I will investigate your original patch that added
regression this afternoon and respond with my observation as soon as
my investigation is complete. I assume, you are trying to make the change
such that the virtual pointers stored in sw_data/pad works across
32bit and 64bit machine, right? 

Murali

quoted

Hence, fix it by partially reverting above commit and restoring
get/set_pad_info() functionality as it was before.

[1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95361.html
Cc: Wingman Kwok <redacted>
Cc: Mugunthan V N <redacted>
CC: David Laight <redacted>
Reported-by: Franklin S Cooper Jr <redacted>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Murali Karicheri <redacted>

I don't think I sent this patch with a 'Signed-off-by', did I?
(I could be misremembering that).

	Arnd

-- 
Murali Karicheri
Linux Kernel, Keystone

On Friday 19 February 2016 13:01:59 Murali Karicheri wrote:

quoted

I have just send v2. I will investigate your original patch that added
regression this afternoon and respond with my observation as soon as
my investigation is complete.

Thanks.

I assume, you are trying to make the change
such that the virtual pointers stored in sw_data/pad works across
32bit and 64bit machine, right? 

Yes, that was the idea. The way I intended it, pointers were supposed
to always get stored in a pair of swdata fields and take up 64 bits,
independent of the architecture.

	Arnd