Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 8965eb19 authored by Takashi Iwai's avatar Takashi Iwai Committed by Ingo Molnar
Browse files

x86/pci: fix broken ISA DMA 



Rene Herman reported:

> commit 8779f2fc
>
> "x86: don't try to allocate from DMA zone at first"
>
> breaks all of ISA DMA. Or all of ALSA ISA DMA at least. All
> ISA soundcards are silent following that commit -- no error
> messages, everything appears fine, just silence.

That patch is buggy. We had an implicit assumption that
dev = NULL for ISA devices that require 24bit DMA.

The recent work on x86 dma_alloc_coherent() breaks the ISA DMA buffer
allocation, which is represented by "dev = NULL" and requires 24bit
DMA implicitly.

Bisected-by: default avatarRene Herman <rene.herman@keyaccess.nl>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Tested-by: default avatarRene Herman <rene.herman@keyaccess.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 492c2e47

arch/x86/kernel/pci-dma.c

+5 −3
Original line number Diff line number Diff line
@@ -385,11 +385,13 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle, 
	if (dma_alloc_from_coherent_mem(dev, size, dma_handle, &memory))

		return memory;



	if (!dev)

	if (!dev) {

		dev = &fallback_dev;

		gfp |= GFP_DMA;

	}

	dma_mask = dev->coherent_dma_mask;

	if (dma_mask == 0)

		dma_mask = DMA_32BIT_MASK;

		dma_mask = (gfp & GFP_DMA) ? DMA_24BIT_MASK : DMA_32BIT_MASK;



	/* Device not DMA able */

	if (dev->dma_mask == NULL)
@@ -403,7 +405,7 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle, 
	   larger than 16MB and in this case we have a chance of

	   finding fitting memory in the next higher zone first. If

	   not retry with true GFP_DMA. -AK */

	if (dma_mask <= DMA_32BIT_MASK)

	if (dma_mask <= DMA_32BIT_MASK && !(gfp & GFP_DMA))

		gfp |= GFP_DMA32;

#endif