Commit 9d8e536d authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: memalloc: Try dma_alloc_noncontiguous() at first 



The latest fix for the non-contiguous memalloc helper changed the
allocation method for a non-IOMMU system to use only the fallback
allocator.  This should have worked, but it caused a problem sometimes
when too many non-contiguous pages are allocated that can't be treated
by HD-audio controller.

As a quirk workaround, go back to the original strategy: use
dma_alloc_noncontiguous() at first, and apply the fallback only when
it fails, but only for non-IOMMU case.

We'll need a better fix in the fallback code as well, but this
workaround should paper over most cases.

Fixes: 9736a325 ("ALSA: memalloc: Don't fall back for SG-buffer with IOMMU")
Reported-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/CAHk-=wgSH5ubdvt76gNwa004ooZAEJL_1Q-Fyw5M2FDdqL==dg@mail.gmail.com
Link: https://lore.kernel.org/r/20221112084718.3305-1-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 9a5523f7

sound/core/memalloc.c

+3 −4
Original line number Diff line number Diff line
@@ -542,8 +542,10 @@ static void *snd_dma_noncontig_alloc(struct snd_dma_buffer *dmab, size_t size) 
	struct sg_table *sgt;

	void *p;



	sgt = dma_alloc_noncontiguous(dmab->dev.dev, size, dmab->dev.dir,

				      DEFAULT_GFP, 0);

#ifdef CONFIG_SND_DMA_SGBUF

	if (!get_dma_ops(dmab->dev.dev)) {

	if (!sgt && !get_dma_ops(dmab->dev.dev)) {

		if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG)

			dmab->dev.type = SNDRV_DMA_TYPE_DEV_WC_SG_FALLBACK;

		else
@@ -551,9 +553,6 @@ static void *snd_dma_noncontig_alloc(struct snd_dma_buffer *dmab, size_t size) 
		return snd_dma_sg_fallback_alloc(dmab, size);

	}

#endif



	sgt = dma_alloc_noncontiguous(dmab->dev.dev, size, dmab->dev.dir,

				      DEFAULT_GFP, 0);

	if (!sgt)

		return NULL;