On Tue, Sep 01, 2020 at 07:12:41PM +0200, Thomas Bogendoerfer wrote:
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:
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.
Well, if IP22 doesn't speculate (which I'm pretty sure is the case), dma_sync_single_for_cpu should indeeed be a no-op. But then there also shouldn't be anything in the cache, as the previous dma_sync_single_for_device should have invalidated it. So it seems like we are missing one (or more) ownership transfers to the device. I'll try to look at the the ownership management in a little more detail tomorrow.