On Tue, Sep 01, 2020 at 05:22:09PM +0200, Thomas Bogendoerfer wrote:

On Wed, Aug 19, 2020 at 08:55:49AM +0200, Christoph Hellwig wrote:

quoted

Use the proper modern API to transfer cache ownership for incoherent DMA.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/net/ethernet/seeq/sgiseeq.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/seeq/sgiseeq.c b/drivers/net/ethernet/seeq/sgiseeq.c
index 39599bbb5d45b6..f91dae16d69a19 100644
--- a/drivers/net/ethernet/seeq/sgiseeq.c
+++ b/drivers/net/ethernet/seeq/sgiseeq.c

@@ -112,14 +112,18 @@ struct sgiseeq_private {
 
 static inline void dma_sync_desc_cpu(struct net_device *dev, void *addr)
 {
-	dma_cache_sync(dev->dev.parent, addr, sizeof(struct sgiseeq_rx_desc),
-		       DMA_FROM_DEVICE);
+	struct sgiseeq_private *sp = netdev_priv(dev);
+
+	dma_sync_single_for_cpu(dev->dev.parent, VIRT_TO_DMA(sp, addr),
+			sizeof(struct sgiseeq_rx_desc), DMA_BIDIRECTIONAL);
 }
 
 static inline void dma_sync_desc_dev(struct net_device *dev, void *addr)
 {
-	dma_cache_sync(dev->dev.parent, addr, sizeof(struct sgiseeq_rx_desc),
-		       DMA_TO_DEVICE);
+	struct sgiseeq_private *sp = netdev_priv(dev);
+
+	dma_sync_single_for_device(dev->dev.parent, VIRT_TO_DMA(sp, addr),
+			sizeof(struct sgiseeq_rx_desc), DMA_BIDIRECTIONAL);
 }

this breaks ethernet on IP22 completely, but I haven't figured out why, yet.

the problem is that dma_sync_single_for_cpu() doesn't flush anything
for IP22, because it only flushes for CPUs which do speculation. So
either MIPS arch_sync_dma_for_cpu() should always flush or sgiseeq
needs to use a different sync funktion, when it wants to re-read descriptors
from memory.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]