RE: [PATCH v2] ASoC: amd: put off registering mach platform_dev to avoid -517 err

["Mukunda, Vijendar" <Vijendar.Mukunda@amd.com>]

> -----Original Message-----
> From: Mukunda, Vijendar
> Sent: Friday, May 22, 2020 8:01 PM
> To: 'Hui Wang' <hui.wang@canonical.com>; Mark Brown
> <broonie@kernel.org>
> Cc: alsa-devel@alsa-project.org
> Subject: RE: [PATCH v2] ASoC: amd: put off registering mach platform_dev to
> avoid -517 err
> 
> [AMD Official Use Only - Internal Distribution Only]
> 
> 
> 
> > -----Original Message-----
> > From: Hui Wang <hui.wang@canonical.com>
> > Sent: Friday, May 22, 2020 7:27 PM
> > To: Mukunda, Vijendar <Vijendar.Mukunda@amd.com>; Mark Brown
> > <broonie@kernel.org>
> > Cc: alsa-devel@alsa-project.org
> > Subject: Re: [PATCH v2] ASoC: amd: put off registering mach platform_dev to
> > avoid -517 err
> >
> >
> > On 2020/5/22 下午8:59, Hui Wang wrote:
> > >
> > > On 2020/5/22 下午7:28, Mukunda, Vijendar wrote:
> > >>
> > >>> -----Original Message-----
> > >>> From: Mark Brown <broonie@kernel.org>
> > >>> Sent: Friday, May 22, 2020 4:52 PM
> > >>> To: Mukunda, Vijendar <Vijendar.Mukunda@amd.com>
> > >>> Cc: Hui Wang <hui.wang@canonical.com>; alsa-devel@alsa-project.org
> > >>> Subject: Re: [PATCH v2] ASoC: amd: put off registering mach
> > >>> platform_dev to
> > >>> avoid -517 err
> > >>>
> > >>> On Fri, May 22, 2020 at 11:13:43AM +0000, Mukunda, Vijendar wrote:
> > >>>
> > >>>> Does sound card registration failure at boot time due to modules
> > >>>> loading
> > >>> order can be considered as bug ?
> > >>>
> > >>> No, this is totally normal.  If it failed to bind ever then that'd be a
> > >>> problem but this is just deferring.
> > >> In that case, we don't need this work around I guess.
> > >> At maximum during boot time, we may see few sound card registration
> > >> failure logs,
> > >> Which is normal.
> > >>
> > >> With this change, our concept of ACP parent device which will create
> > >> platform devices
> > >> for DMA driver, Generic DMIC driver and Machine driver will be changed.
> > >> We implemented same design for Raven I2S driver as well which got
> > >> productized.
> > >>
> > > OK, got it.  It doesn't affect the sound function anyway.
> >
> > BTW, so far, I have not seen the -517 error from ubuntu kernel dmesg on
> > PC or laptop. Maybe this is the 1st driver to print this error in the
> > dmesg on PC or laptop, so I guess it probably confuses the users or our QA.
> >
> 
> We have similar design for I2S endpoint which got productized on other OS
> variant.
> Most of the PC and Laptop comes up with Legacy HD Audio Driver solution.
> This is ASoC based driver.
> As this failure message only appears during boot time,  Its okay to go ahead.
> End user should really worry if sound card is not created even after system
> boots up.

I have seen sample implementation of deferred probe in one of the machine
driver code using late_initcall() API.
Not sure how this api really works which will resolve the modules loading sequence
issue.