Re: [PATCH 0/4] ASoC: Drop soc-topology ABI v4 support

[Cezary Rojewski <cezary.rojewski@xxxxxxxxx>]

On 2024-04-03 5:53 PM, Mark Brown wrote:
> On Wed, Apr 03, 2024 at 11:16:25AM +0200, Cezary Rojewski wrote:
> > This patchset impacts UAPI.
>
> > The only known users of the soc-topology ABI v4 are Chromebook
> > configurations. Starting from kernel v5.4, all of them are making use of
> > soc-topology ABI v5. The patchset first removes obsolete code from the
> > Intel's skylake-driver - the driver of choice for the mentioned
> > Chromebooks - and then proceeds with removal of relevant soc-topology.c
> > and uapi bits.
>
> Do we have to worry about old Chromebooks that fell out of ChromeOS
> support but people are still using with a general purpose distro?  I'm
> not sure what the user community is like there but v5.4 is from 2019
> (and products would I guess have still been coming out for earlier
> things in 2020) which feels kind of recent.

+Radoslaw


Short answer: I believe we do not have to worry about these.

Longer answer. Intel topology utilized with the skylake-driver has been 
versioned as:
- 0065, paired with topology ABI v4, status: obsolete, never upstreamed
- 0071, paired with topology ABI v4, status: obsolete, never upstreamed
- 0072, paired with topology ABI v5, status: maintenance

To my knowledge, following are Chromebook systems currently outside of 
the support window:

Broadwell-based:	N/A - no topology, catpt-driver
Braswell-based:		N/A - no topology, atom-driver
Skylake-Y-based:	v4.19, skylake-driver
<anything younger has been transitioned to ABI v5>

By younger I mean: any platform supported by upstream skylake-driver 
kernel v5.4 and onward -or- the avs-driver. So, the Skylake-Y platforms 
are the only subject to be discussed if at all.

To my knowledge #2 the upstream version of skylake-driver on v4.19 
kernel breaks when utilizing old topology, the so-called 0065 -or- 0071 
which are based on soc-topology ABI v4. When it does work, it's because 
of internal patches for the kernel. Switching away from the native 
system into general purpose distro on such Chromebooks may translate to 
necessary patches missing, breaking audio in the process. Only the 
topology files for 0072 have ever been shared to the public [1].

User may also utilize the avs-driver on such machines provided they 
upgrade their kernel as we did share working files [2] for machine board 
drivers for ssm4567 and max98357a cases - onboard codecs present on 
Skylake-Y platforms.


[1]: 
https://github.com/thesofproject/avs-topology-xml/tree/for-skylake-driver?tab=readme-ov-file#supported-configurations
[2]: https://github.com/thesofproject/avs-topology-xml/releases/tag/v2024.02


Kind regards,
Czarek