Re: [PATCH 4/7] ALSA: pcm: use dma_can_mmap() to check if a device supports dma_mmap_*
From: Takashi Iwai <hidden>
Date: 2019-08-05 09:22:02
Also in:
linux-arm-kernel, linux-iommu, linux-sh, lkml
On Mon, 05 Aug 2019 11:11:56 +0200, Christoph Hellwig wrote:
quoted hunk ↗ jump to hunk
Replace the local hack with the dma_can_mmap helper to check if a given device supports mapping DMA allocations to userspace. Signed-off-by: Christoph Hellwig <hch@lst.de> --- sound/core/pcm_native.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index 703857aab00f..81c82c3ee8a2 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c@@ -220,12 +220,11 @@ static bool hw_support_mmap(struct snd_pcm_substream *substream) { if (!(substream->runtime->hw.info & SNDRV_PCM_INFO_MMAP)) return false; - /* architecture supports dma_mmap_coherent()? */ -#if defined(CONFIG_ARCH_NO_COHERENT_DMA_MMAP) || !defined(CONFIG_HAS_DMA) + if (!dma_can_mmap(substream->dma_buffer.dev.dev)) + return false; if (!substream->ops->mmap && substream->dma_buffer.dev.type == SNDRV_DMA_TYPE_DEV) return false; -#endif
This won't work as expected, unfortunately. It's a bit tricky check, since the driver may have its own mmap implementation via substream->ops->mmap, and the dma_buffer.dev.dev might point to another object depending on the dma_buffer.dev.type. So please replace with something like below:
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c@@ -221,11 +221,10 @@ static bool hw_support_mmap(struct snd_pcm_substream *substream) if (!(substream->runtime->hw.info & SNDRV_PCM_INFO_MMAP)) return false; /* architecture supports dma_mmap_coherent()? */ -#if defined(CONFIG_ARCH_NO_COHERENT_DMA_MMAP) || !defined(CONFIG_HAS_DMA) if (!substream->ops->mmap && - substream->dma_buffer.dev.type == SNDRV_DMA_TYPE_DEV) + substream->dma_buffer.dev.type == SNDRV_DMA_TYPE_DEV && + !dma_can_mmap(substream->dma_buffer.dev.dev)) return false; -#endif return true; }
Thanks! Takashi