[PATCH v2 0/2] dmaengine: omap-dma: Fix polled completion

Hi,

Based on the discussion on the first version:
https://lkml.org/lkml/2016/2/25/167

I have fixed the omap_dma_tx_status() - first patch and added the second patch
to not disable the interrupts for memcpy so multiple transfers can be queued.

Regards,
Peter
---
Peter Ujfalusi (2):
  dmaengine: omap-dma: Fix polled channel completion detection and
    handling
  dmaengine: omap-dma: Do not suppress interrupts for memcpy

 drivers/dma/omap-dma.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

-- 
2.7.2

If the client queues up more transfers the driver will not able to move to
the next transfer without knowing that the previous descriptor is
completed.

Signed-off-by: Peter Ujfalusi <redacted>
---
 drivers/dma/omap-dma.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/dma/omap-dma.c b/drivers/dma/omap-dma.c
index a37001f72ebf..f7498681be82 100644
--- a/drivers/dma/omap-dma.c
+++ b/drivers/dma/omap-dma.c

@@ -953,9 +953,7 @@ static struct dma_async_tx_descriptor *omap_dma_prep_dma_memcpy(
 	d->ccr = c->ccr;
 	d->ccr |= CCR_DST_AMODE_POSTINC | CCR_SRC_AMODE_POSTINC;
 
-	d->cicr = CICR_DROP_IE;
-	if (tx_flags & DMA_PREP_INTERRUPT)
-		d->cicr |= CICR_FRAME_IE;
+	d->cicr = CICR_DROP_IE | CICR_FRAME_IE;
 
 	d->csdp = data_type;
 

-- 
2.7.2

When based on the CCR_ENABLE bit the channel is stopped we should not call
omap_dma_callback(), only change the return value to DMA_COMPLETE. Client
drivers will do the right thing to clean up the channel after the transfer
has been completed.
Check the CCR_ENABLE only if the channel is running and not paused since
pause in sDMA means that the channel is stopped.
This will fix one hard to reproduce race condition when the channel is
terminated during transfer (affecting cyclic operation).

Fixes: 1a7cf7b26f25 ("dmaengine: omap-dma: Handle cases when the channel is polled for completion")

Signed-off-by: Peter Ujfalusi <redacted>
---
 drivers/dma/omap-dma.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/dma/omap-dma.c b/drivers/dma/omap-dma.c
index f6bef0d93998..a37001f72ebf 100644
--- a/drivers/dma/omap-dma.c
+++ b/drivers/dma/omap-dma.c

@@ -48,6 +48,7 @@ struct omap_chan {
 	unsigned dma_sig;
 	bool cyclic;
 	bool paused;
+	bool running;
 
 	int dma_ch;
 	struct omap_desc *desc;

@@ -294,6 +295,8 @@ static void omap_dma_start(struct omap_chan *c, struct omap_desc *d)
 
 	/* Enable channel */
 	omap_dma_chan_write(c, CCR, d->ccr | CCR_ENABLE);
+
+	c->running = true;
 }
 
 static void omap_dma_stop(struct omap_chan *c)

@@ -355,6 +358,8 @@ static void omap_dma_stop(struct omap_chan *c)
 
 		omap_dma_chan_write(c, CLNK_CTRL, val);
 	}
+
+	c->running = false;
 }
 
 static void omap_dma_start_sg(struct omap_chan *c, struct omap_desc *d)

@@ -671,15 +676,20 @@ static enum dma_status omap_dma_tx_status(struct dma_chan *chan,
 	struct omap_chan *c = to_omap_dma_chan(chan);
 	struct virt_dma_desc *vd;
 	enum dma_status ret;
-	uint32_t ccr;
 	unsigned long flags;
 
-	ccr = omap_dma_chan_read(c, CCR);
-	/* The channel is no longer active, handle the completion right away */
-	if (!(ccr & CCR_ENABLE))
-		omap_dma_callback(c->dma_ch, 0, c);
-
 	ret = dma_cookie_status(chan, cookie, txstate);
+
+	if (!c->paused && c->running) {
+		uint32_t ccr = omap_dma_chan_read(c, CCR);
+		/*
+		 * The channel is no longer active, set the return value
+		 * accordingly
+		 */
+		if (!(ccr & CCR_ENABLE))
+			ret = DMA_COMPLETE;
+	}
+
 	if (ret == DMA_COMPLETE || !txstate)
 		return ret;
 

-- 
2.7.2

On Thu, Mar 10, 2016 at 03:28:45PM +0200, Peter Ujfalusi wrote:

Hi,

Based on the discussion on the first version:
https://lkml.org/lkml/2016/2/25/167

I have fixed the omap_dma_tx_status() - first patch and added the second patch
to not disable the interrupts for memcpy so multiple transfers can be queued.

Hi Peter,

These do not apply for me. Can you please check.

FWIW my fixes is on -rc1

-- 
~Vinod

Hi Vinod,

On 04/04/16 16:18, Vinod Koul wrote:

On Thu, Mar 10, 2016 at 03:28:45PM +0200, Peter Ujfalusi wrote:

quoted

Hi,

Based on the discussion on the first version:
https://lkml.org/lkml/2016/2/25/167

I have fixed the omap_dma_tx_status() - first patch and added the second patch
to not disable the interrupts for memcpy so multiple transfers can be queued.

Hi Peter,

These do not apply for me. Can you please check.

I have resent as v3.

FWIW my fixes is on -rc1

tested with -rc1

-- 
P?ter