ALSA: pcm: Check mmap capability of runtime dma buffer at first

Currently we check only the substream->dma_buffer as the preset of the
buffer configuration for verifying the availability of mmap.  But a
few drivers rather set up the buffer in the own way without the
standard buffer preallocation using substream->dma_buffer, and they
miss the proper checks.  (Now it's working more or less fine as most
of them are running only on x86).

Actually, they may set up the runtime dma_buffer (referred via
snd_pcm_get_dma_buf()) at the open callback, though.  That is, this
could have been used as the primary source.

This patch changes the hw_support_mmap() function to check the runtime
dma buffer at first.  It's usually NULL with the standard buffer
preallocation, and in that case, we continue checking
substream->dma_buffer as fallback.

Link: https://lore.kernel.org/r/20210809071829.22238-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 71323d8..dc9fa31 100644 (file)
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -243,13 +243,18 @@ int snd_pcm_info_user(struct snd_pcm_substream *substream,
 
 static bool hw_support_mmap(struct snd_pcm_substream *substream)
 {
+       struct snd_dma_buffer *dmabuf;
+
        if (!(substream->runtime->hw.info & SNDRV_PCM_INFO_MMAP))
                return false;
 
        if (substream->ops->mmap || substream->ops->page)
                return true;
 
-       switch (substream->dma_buffer.dev.type) {
+       dmabuf = snd_pcm_get_dma_buf(substream);
+       if (!dmabuf)
+               dmabuf = &substream->dma_buffer;
+       switch (dmabuf->dev.type) {
        case SNDRV_DMA_TYPE_UNKNOWN:
                /* we can't know the device, so just assume that the driver does
                 * everything right
@@ -259,7 +264,7 @@ static bool hw_support_mmap(struct snd_pcm_substream *substream)
        case SNDRV_DMA_TYPE_VMALLOC:
                return true;
        default:
-               return dma_can_mmap(substream->dma_buffer.dev.dev);
+               return dma_can_mmap(dmabuf->dev.dev);
        }
 }