Kernel 5.13.6 breaks mmap with snd-hdsp module
Jeff Woods
jwoods at fnordco.com
Sun Aug 8 21:09:38 CEST 2021
---- On Sun, 08 Aug 2021 00:01:16 -0700 Takashi Iwai <tiwai at suse.de> wrote ----
> On Sun, 08 Aug 2021 00:51:35 +0200,
> Jeff Woods wrote:
> >
> > ---- On Sat, 07 Aug 2021 02:26:32 -0700 Takashi Iwai <tiwai at suse.de> wrote ----
> > > On Sat, 07 Aug 2021 10:16:47 +0200,
> > > Greg KH wrote:
> > > >
> > > > On Sat, Aug 07, 2021 at 12:49:07AM -0700, Jeff Woods wrote:
> > > > > Specifically, commit c4824ae7db418aee6f50f308a20b832e58e997fd triggers the problem. Reverting this change restores functionality.
> > > > >
> > > > > The device is an RME Multiface II, using the snd-hdsp driver.
> > > > >
> > > > > Expected behavior: Device plays sound normally
> > > > >
> > > > > Exhibited behavior: When a program attempts to open the device, the following ALSA lib error happens:
> > > > >
> > > > > ALSA lib pcm_direct.c:1169:(snd1_pcm_direct_initialize_slave) slave plugin does not support mmap interleaved or mmap noninterleaved access
> > > > >
> > > > > This change hasn't affected my other computers with less esoteric hardware, so probably the problem lies with the snd-hdsp driver, but the device is unusable without reverting that commit.
> > > > >
> > > > > I am available to test any patches for this issue.
> > > >
> > > > Have you notified the developers involved in this change about this
> > > > issue?
> > >
> > > No, it's a new report :)
> > >
> > > > Adding them now...
> > >
> > > Could you try the patch below?
> > >
> > >
> > > thanks,
> > >
> > > Takashi
> > >
> > > -- 8< --
> > > From: Takashi Iwai <tiwai at suse.de>
> > > Subject: [PATCH] ALSA: pci: rme: Fix mmap breakage
> > >
> > > The recent change in the PCM core restricts the mmap of unknown buffer
> > > type, and this broke the mmap on RME9652 and HDSP drivers that didn't
> > > set up properly. Actually those driver do use the buffers allocated
> > > in a standard way, and the proper calls should fix the breakage.
> > >
> > > Fixes: c4824ae7db41 ("ALSA: pcm: Fix mmap capability check")
> > > Cc: <stable at vger.kernel.org>
> > > Signed-off-by: Takashi Iwai <tiwai at suse.de>
> > > ---
> > > sound/pci/rme9652/hdsp.c | 6 ++----
> > > sound/pci/rme9652/rme9652.c | 6 ++----
> > > 2 files changed, 4 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/sound/pci/rme9652/hdsp.c b/sound/pci/rme9652/hdsp.c
> > > index 8457a4bbc3df..b32a72e28917 100644
> > > --- a/sound/pci/rme9652/hdsp.c
> > > +++ b/sound/pci/rme9652/hdsp.c
> > > @@ -4518,8 +4518,7 @@ static int snd_hdsp_playback_open(struct snd_pcm_substream *substream)
> > > snd_pcm_set_sync(substream);
> > >
> > > runtime->hw = snd_hdsp_playback_subinfo;
> > > - runtime->dma_area = hdsp->playback_buffer;
> > > - runtime->dma_bytes = HDSP_DMA_AREA_BYTES;
> > > + snd_pcm_set_runtime_buffer(substream, hdsp->playback_dma_buf);
> > >
> > > hdsp->playback_pid = current->pid;
> > > hdsp->playback_substream = substream;
> > > @@ -4595,8 +4594,7 @@ static int snd_hdsp_capture_open(struct snd_pcm_substream *substream)
> > > snd_pcm_set_sync(substream);
> > >
> > > runtime->hw = snd_hdsp_capture_subinfo;
> > > - runtime->dma_area = hdsp->capture_buffer;
> > > - runtime->dma_bytes = HDSP_DMA_AREA_BYTES;
> > > + snd_pcm_set_runtime_buffer(substream, hdsp->capture_dma_buf);
> > >
> > > hdsp->capture_pid = current->pid;
> > > hdsp->capture_substream = substream;
> > > diff --git a/sound/pci/rme9652/rme9652.c b/sound/pci/rme9652/rme9652.c
> > > index f1aad38760d6..8036ed761d53 100644
> > > --- a/sound/pci/rme9652/rme9652.c
> > > +++ b/sound/pci/rme9652/rme9652.c
> > > @@ -2279,8 +2279,7 @@ static int snd_rme9652_playback_open(struct snd_pcm_substream *substream)
> > > snd_pcm_set_sync(substream);
> > >
> > > runtime->hw = snd_rme9652_playback_subinfo;
> > > - runtime->dma_area = rme9652->playback_buffer;
> > > - runtime->dma_bytes = RME9652_DMA_AREA_BYTES;
> > > + snd_pcm_set_runtime_buffer(substream, rme9652->playback_dma_buf);
> > >
> > > if (rme9652->capture_substream == NULL) {
> > > rme9652_stop(rme9652);
> > > @@ -2339,8 +2338,7 @@ static int snd_rme9652_capture_open(struct snd_pcm_substream *substream)
> > > snd_pcm_set_sync(substream);
> > >
> > > runtime->hw = snd_rme9652_capture_subinfo;
> > > - runtime->dma_area = rme9652->capture_buffer;
> > > - runtime->dma_bytes = RME9652_DMA_AREA_BYTES;
> > > + snd_pcm_set_runtime_buffer(substream, rme9652->capture_dma_buf);
> > >
> > > if (rme9652->playback_substream == NULL) {
> > > rme9652_stop(rme9652);
> > > --
> > > 2.26.2
> > >
> >
> > I applied the patch to kernel 5.13.8, but compilation fails with these errors:
>
> Oops, sorry, that was the patch for linux-next, and I forgot the
> recent code change. And it turned out not to be effective.
>
> Below is another try. Scratch the previous one (although it cannot
> hurt), and try this one instead.
>
>
> thanks,
>
> Takashi
>
> -- 8< --
> From: Takashi Iwai <tiwai at suse.de>
> Subject: [PATCH] ALSA: pcm: Fix mmap breakage without explicit buffer setup
>
> The recent fix c4824ae7db41 ("ALSA: pcm: Fix mmap capability check")
> restricts the mmap capability only to the drivers that properly set up
> the buffers, but it caused a regression for a few drivers that manage
> the buffer on its own way.
>
> For those with UNKNOWN buffer type (i.e. the uninitialized / unused
> substream->dma_buffer), just assume that the driver handles the mmap
> properly and blindly trust the hardware info bit.
>
> Fixes: c4824ae7db41 ("ALSA: pcm: Fix mmap capability check")
> Cc: <stable at vger.kernel.org>
> Signed-off-by: Takashi Iwai <tiwai at suse.de>
> ---
> sound/core/pcm_native.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
> index 09c0e2a6489c..71323d807dbf 100644
> --- a/sound/core/pcm_native.c
> +++ b/sound/core/pcm_native.c
> @@ -251,7 +251,10 @@ static bool hw_support_mmap(struct snd_pcm_substream *substream)
>
> switch (substream->dma_buffer.dev.type) {
> case SNDRV_DMA_TYPE_UNKNOWN:
> - return false;
> + /* we can't know the device, so just assume that the driver does
> + * everything right
> + */
> + return true;
> case SNDRV_DMA_TYPE_CONTINUOUS:
> case SNDRV_DMA_TYPE_VMALLOC:
> return true;
> --
> 2.26.2
>
>
I applied the patch to 5.13.9, and it did indeed solve the problem.
Thank you very much!
For future reference, if I am reporting an issue with stable and I know the
commit that caused it, should I contact the committer directly *and* cc the
stable and regressions list?
I'm trying to keep protocol and not spam things up too much.
Thanks,
Jeff
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