[PATCH v2 0/3] Fix SND_HDA_PREALLOC issue

[Takashi Iwai]

On Thu, 18 Mar 2021 17:06:15 +0100,
Amadeusz Sławiński wrote:
> 
> For context it started with user reporting failures when running arecord
> without any error or warning in dmesg (after fixing some configuration
> problems thet they had).
> https://bugzilla.kernel.org/show_bug.cgi?id=201251#c279
> 
> After spending time investigating the issue it was narrowed to quite big
> setting of CONFIG_SND_HDA_PREALLOC_SIZE (4096).
> When looking at code
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/sound/core/pcm_memory.c?id=6417f03132a6952cd17ddd8eaddbac92b61b17e0#n30
> there is a limit of memory per card:
> max_alloc_per_card = 32UL * 1024UL * 1024UL
> 
> When SND_HDA_PREALLOC_SIZE is set to 4096 it only has memory to alloc
> for 8 frontends, while Skylake HDA card has 10 of them (6 playback and 4
> capture), so preallocated memory is exhausted while probing. In
> consequence 2 of FEs end without allocated memory.
> 
> It can be workarounded on user side with setting SND_HDA_PREALLOC_SIZE
> to lower value, other is changing memory limit per card.
> 
> However in order to not waste user memory, change maximum allocation
> size on HDA controller to 4MB and force automatical memory allocation
> insted of preallocated one.
> 
> First patch adds prints, so similar issues can be easily identified in
> the future.
> Second changes maximum size of hda buffer to reasonable value of 4MB.
> And last one reverts patch which allowed setting prealloc size on X86
> platforms.
> 
> Amadeusz Sławiński (3):
>   ALSA: pcm: Add debug print on memory allocation failure
>   ALSA: hda: Change AZX_MAX_BUF_SIZE from 1GB to 4MB
>   ALSA: hda: Revert "ALSA: hda: Allow setting preallocation again for
>     x86"

Applied all three patches now.  Thanks.


Takashi