Re: Kernel 5.13.6 breaks mmap with snd-hdsp module

[Jeff Woods <jwoods@fnordco.com>]

 ---- On Sat, 07 Aug 2021 02:26:32 -0700 Takashi Iwai <tiwai@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@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@vger.kernel.org>
 > Signed-off-by: Takashi Iwai <tiwai@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:

sound/pci/rme9652/hdsp.c: In function ‘snd_hdsp_playback_open’:
sound/pci/rme9652/hdsp.c:4505:51: error: incompatible type for argument 2 of ‘snd_pcm_set_runtime_buffer’
 4505 |         snd_pcm_set_runtime_buffer(substream, hdsp->playback_dma_buf);
      |                                               ~~~~^~~~~~~~~~~~~~~~~~
      |                                                   |
      |                                                   struct snd_dma_buffer
In file included from sound/pci/rme9652/hdsp.c:23:
./include/sound/pcm.h:1154:70: note: expected ‘struct snd_dma_buffer *’ but argument is of type ‘struct snd_dma_buffer’
 1154 |                                               struct snd_dma_buffer *bufp)
      |                                               ~~~~~~~~~~~~~~~~~~~~~~~^~~~
sound/pci/rme9652/hdsp.c: In function ‘snd_hdsp_capture_open’:
sound/pci/rme9652/hdsp.c:4581:51: error: incompatible type for argument 2 of ‘snd_pcm_set_runtime_buffer’
 4581 |         snd_pcm_set_runtime_buffer(substream, hdsp->capture_dma_buf);
      |                                               ~~~~^~~~~~~~~~~~~~~~~
      |                                                   |
      |                                                   struct snd_dma_buffer
In file included from sound/pci/rme9652/hdsp.c:23:
./include/sound/pcm.h:1154:70: note: expected ‘struct snd_dma_buffer *’ but argument is of type ‘struct snd_dma_buffer’
 1154 |                                               struct snd_dma_buffer *bufp)
      |                                               ~~~~~~~~~~~~~~~~~~~~~~~^~~~
make[3]: *** [scripts/Makefile.build:273: sound/pci/rme9652/hdsp.o] Error 1
make[2]: *** [scripts/Makefile.build:516: sound/pci/rme9652] Error 2
make[1]: *** [scripts/Makefile.build:516: sound/pci] Error 2

I also patched and compiled 5.14-rc4, but got the same errors.

Next I tried cloning git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git.

The patch applied and compiled, but I get the same "does not support mmap" error when trying to play anything.

Let me know if there's any other info I can provide.

Thanks,
Jeff