Re: [PATCH 01/13] ALSA: pcm: add more sample rate definitions

[Jaroslav Kysela]

On 11. 09. 24 12:51, Takashi Iwai wrote:
> On Wed, 11 Sep 2024 12:33:01 +0200,
> Péter Ujfalusi wrote:
> > On 11/09/2024 12:21, Takashi Iwai wrote:
> > > > Wondering if this is backwards compatible with the alsa-lib definitions,
> > > > specifically the topology parts which did unfortunately have a list of
> > > > rates that will map to a different index now:
> > > >
> > > >
> > > > typedef enum _snd_pcm_rates {
> > > > 	SND_PCM_RATE_UNKNOWN = -1,
> > > > 	SND_PCM_RATE_5512 = 0,
> > > > 	SND_PCM_RATE_8000,
> > > > 	SND_PCM_RATE_11025,
> > > > 	SND_PCM_RATE_16000,
> > > > 	SND_PCM_RATE_22050,
> > > > 	SND_PCM_RATE_32000,
> > > > 	SND_PCM_RATE_44100,
> > > > 	SND_PCM_RATE_48000,
> > > > 	SND_PCM_RATE_64000,
> > > > 	SND_PCM_RATE_88200,
> > > > 	SND_PCM_RATE_96000,
> > > > 	SND_PCM_RATE_176400,
> > > > 	SND_PCM_RATE_192000,
> > > > 	SND_PCM_RATE_CONTINUOUS = 30,
> > > > 	SND_PCM_RATE_KNOT = 31,
> > > > 	SND_PCM_RATE_LAST = SND_PCM_RATE_KNOT,
> > > > } snd_pcm_rates_t;
> > >
> > > As far as I understand correctly, those rate bits used for topology
> > > are independent from the bits used for PCM core, although it used to
> > > be the same.  Maybe better to rename (such as SND_TPLG_RATE_*) so that
> > > it's clearer only for topology stuff.
> >
> > Even if we rename these in alsa-lib we will need translation from
> > SND_TPLG_RATE_ to SND_PCM_RATE_ in kernel likely?
> >
> > The topology files are out there and this is an ABI...
> >
> > > But it'd be better if anyone can double-check.
> >
> > Since the kernel just copies the rates bitfield, any rate above 11025
> > will be misaligned and result broken setup.
>
> Yep, I noticed it now, too.
>
> Below is the fix patch, totally untested.
> It'd be appreciated if anyone can test it quickly.
>
>
> thanks,
>
> Takashi
>
> -- 8< --
> From: Takashi Iwai <tiwai@xxxxxxx>
> Subject: [PATCH] ALSA: pcm: Fix breakage of PCM rates used for topology
>
> It turned out that the topology ABI takes the standard PCM rate bits
> as is, and it means that the recent change of the PCM rate bits would
> lead to the inconsistent rate values used for topology.
>
> This patch reverts the original PCM rate bit definitions while adding
> the new rates to the extended bits instead.  This needed the change of
> snd_pcm_known_rates, too.  And this also required to fix the handling
> in snd_pcm_hw_limit_rates() that blindly assumed that the list is
> sorted while it became unsorted now.
>
> Fixes: 090624b7dc83 ("ALSA: pcm: add more sample rate definitions")
> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>

This looks fine. But the topology rate bits should not depend on those bits. 
It's a bit pitty that the standard PCM ABI does not use those bits for user 
space and we are doing this change just for topology ABI.

Reviewed-by: Jaroslav Kysela <perex@xxxxxxxx>

--
Jaroslav Kysela <perex@xxxxxxxx>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.