Re: [RFC PATCH v2 4/6] ASoC: fsl_asrc_m2m: Add memory to memory function

[Jaroslav Kysela <perex@xxxxxxxx>]

On 20. 08. 24 9:37, Shengjiu Wang wrote:
> On Tue, Aug 20, 2024 at 2:59 PM Pierre-Louis Bossart
> <pierre-louis.bossart@xxxxxxxxxxxxxxx> wrote:
> > On 8/20/24 04:53, Shengjiu Wang wrote:
> > > On Mon, Aug 19, 2024 at 3:42 PM Pierre-Louis Bossart
> > > <pierre-louis.bossart@xxxxxxxxxxxxxxx> wrote:
> > > > On 8/16/24 12:42, Shengjiu Wang wrote:
> > > > > Implement the ASRC memory to memory function using
> > > > > the compress framework, user can use this function with
> > > > > compress ioctl interface.
> > > > >
> > > > > Define below private metadata key value for output
> > > > > format, output rate and ratio modifier configuration.
> > > > > ASRC_OUTPUT_FORMAT 0x80000001
> > > > > ASRC_OUTPUT_RATE   0x80000002
> > > > > ASRC_RATIO_MOD     0x80000003
> > > >
> > > > Can the output format/rate change at run-time?
> > >
> > > Seldom I think.
> > >
> > > > If no, then these parameters should be moved somewhere else - e.g.
> > > > hw_params or something.
> > >
> > > This means I will do some changes in compress_params.h, add
> > > output format and output rate definition, follow Jaroslav's example
> > > right?
> >
> > yes, having parameters for the PCM case would make sense.
> >
> > > > I am still not very clear on the expanding the SET_METADATA ioctl to
> > > > deal with the ratio changes. This isn't linked to the control layer as
> > > > suggested before, and there's no precedent of calling it multiple times
> > > > during streaming.
> > >
> > > Which control layer? if you means the snd_kcontrol_new?  it is bound
> > > with sound card,  but in my case,  I need to the control bind with
> > > the snd_compr_stream to support multi streams/instances.
> >
> > I can only quote Jaroslav's previous answer:
> >
> > "
> > This argument is not valid. The controls are bound to the card, but the
> > element identifiers have already iface (interface), device and subdevice
> > numbers. We are using controls for PCM devices for example. The binding
> > is straight.
> >
> > Just add SNDRV_CTL_ELEM_IFACE_COMPRESS define and specify the compress
> > device number in the 'struct snd_ctl_elem_id'.
> > "
>
> I don't think it is doable,  or at least I don't know how to do it.
>
> My case is just one card/one device/one subdevice.  can't use it to
> distinguish multi streams.

I already wrote that the compress core code should be extended to support 
subdevices like other ALSA APIs. I'll work on it. For now, just add support 
for one converter.

					Jaroslav

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