[PATCH] ALSA: core - add more card sysfs entries

[Curtis Malainey]

On Thu, Apr 8, 2021 at 12:43 PM Pierre-Louis Bossart <
pierre-louis.bossart at linux.intel.com> wrote:

>
>
>
> >>> Yes, I'm talking about rules which depends on the sound driver
> specific sysfs
> >>> attributes (you can match the modified /sys/module/*/parameters here).
> >>
> >> you lost me with 'match the modified parameters' wording. who matches
> >> and who modifies those parameters?
> >
> > You can probably add something like this to the sound-card.rules:
> >
> > SUBSYSTEMS=="pci",ATTR{device/driver/module}=="snd_soc_sof_sdw",
> >
> ATTR{device/driver/module/../snd_sof_pci/parameters/tplg_path}=="intel/sof-tplg/pdm1",
> >    DO_SOMETHING_HERE
> >
> > DO_SOMETHING_HERE may be ATTR{longname}="My Long Name" for example when
> my change is accepted.
>
> Humm, not sure this can work due to dependencies.
>
> The machine device is neither an ACPI nor PCI one. It's a platform device.
>
> When the PCI device is detected, the PCI core will call the SOF driver
> probe, which will first try and boot the firmware, and then create the
> platform device. That results in the probe of the machine driver which
> creates the card, but that happens *after* booting the firmware.
>
> the DSP firmware is setup starting here:
>
> https://elixir.bootlin.com/linux/latest/source/sound/soc/sof/core.c#L138
>
> and the machine device is created almost last, after registering the
> ASoC components.
>
> https://elixir.bootlin.com/linux/latest/source/sound/soc/sof/core.c#L234
>
> when the card is created, it's too late to change the firmware path or
> any firmware-related parameters.
>
>
>
Thanks for raising this to my attention Pierre, yes we are also
experiencing a similar issue since chromium builds will have default sof
tplg and fw, but chrome builds will not. Since our UCMs are in a single
location right now they will contain commands that will not execute on the
defaults and we have no way of indicating to our audio server how to handle
this. I am definitely interested in seeing a feature where we can pass
indicators to the UCM about what we have available.