Robin Murphy robin.murphy@arm.com writes:
On 2022-03-24 10:25, Oleksandr Natalenko wrote:
Hello.
On čtvrtek 24. března 2022 6:57:32 CET Christoph Hellwig wrote:
On Wed, Mar 23, 2022 at 08:54:08PM +0000, Robin Murphy wrote:
I'll admit I still never quite grasped the reason for also adding the override to swiotlb_sync_single_for_device() in aa6f8dcbab47, but I think by that point we were increasingly tired and confused and starting to second-guess ourselves (well, I was, at least). I don't think it's wrong per se, but as I said I do think it can bite anyone who's been doing dma_sync_*() wrong but getting away with it until now. If ddbd89deb7d3 alone turns out to work OK then I'd be inclined to try a partial revert of just that one hunk.
Agreed. Let's try that first.
Oleksandr, can you try the patch below:
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 6db1c475ec827..6c350555e5a1c 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -701,13 +701,10 @@ void swiotlb_tbl_unmap_single(struct device *dev, phys_addr_t tlb_addr, void swiotlb_sync_single_for_device(struct device *dev, phys_addr_t tlb_addr, size_t size, enum dma_data_direction dir) {
- /*
* Unconditional bounce is necessary to avoid corruption on* sync_*_for_cpu or dma_ummap_* when the device didn't overwrite* the whole lengt of the bounce buffer.*/- swiotlb_bounce(dev, tlb_addr, size, DMA_TO_DEVICE);
- BUG_ON(!valid_dma_direction(dir));
- if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)
swiotlb_bounce(dev, tlb_addr, size, DMA_TO_DEVICE);- else
BUG_ON(dir != DMA_FROM_DEVICE);void swiotlb_sync_single_for_cpu(struct device *dev, phys_addr_t tlb_addr,
With this patch the AP works for me.
Cool, thanks for confirming. So I think ath9k probably is doing something dodgy with dma_sync_*(), but if Linus prefers to make the above change rather than wait for that to get figured out, I believe that should be fine.
I'm looking into this; but in the interest of a speedy resolution of the regression I would be in favour of merging that partial revert and reinstating it if/when we identify (and fix) any bugs in ath9k :)
-Toke