RE: [PATCH] ASoC: da7219: Fix general protection fault in da7219_register_dai_clks

From: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
To: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
	Mark Brown <broonie@kernel.org>,
	Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Cc: "alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>,
	"Zhi, Yong" <yong.zhi@intel.com>
Subject: RE: [PATCH] ASoC: da7219: Fix general protection fault in da7219_register_dai_clks
Date: Thu, 30 Jul 2020 19:15:47 +0000	[thread overview]
Message-ID: <AM7PR10MB364075C56DA64BBA164A58A480710@AM7PR10MB3640.EURPRD10.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <6381232d-8226-fd0a-37bc-6bc42451b5e3@linux.intel.com>

On 30 July 2020 17:58, Pierre-Louis Bossart wrote: 

> >>> When the card was uninstalled with modprobe -r, the da7219 codec was not
> >>> removed, only component da7219_remove() is invoked, do you suggest the
> >>> component driver probe and remove has to happen with da7219_i2_driver
> probe
> >>> and remove together? Thanks for the code review.
> >
> >> Well as far as I understand it the the devm_* allocated resources are tied to
> >> the i2c dev. If I'm correct then unless that's removed then those resources
> >> won't be freed. If this is a valid scenario then we would probably have to look
> >> at avoiding all devm_ calls in the da7219_probe() code as they wouldn't be
> >> released when doing what you are here.
> >
> >> Mark, what's your take on this? Am I missing something obvious?
> >
> > You're not missing anything, you shouldn't be doing devm allocations at
> > the CODEC level only at the device model level.  I'm somewhat confused
> > why you would be registering clocks at the device model level TBH.

Ignorance on my part when I wrote the code I'd say.

> 
> I am afraid we have quite a few codec drivers used in x86/ACPI platforms
> using devm_ clk functions at the component probe level...see e.g.:
> 
> da7213, da7218, da7219, es8316, es8328, max98090, max98095, rt5514,
> rt5616, rt5640, rt5682, tlk320aic32x4
> 
> some do even worse: nau8825, tlv320aic32x4 call devm_ functions in
> set_sysclk.
> 
> The module load/unload tests used for SOF remove all the drivers, so as
> Adam was saying this should not happen if you remove the codec driver.
> 
> It already took us quite a bit of effort to make sure all resources are
> properly allocated/released. We still have known issues when removing
> the platform driver only, mainly with HDaudio. I wasn't aware of this
> case for I2C codecs, I guess this just made the list of TODO cleanups
> even longer. D'oh!

Well, I'll make sure I at least sort the da721x drivers to rectify this
discrepancy and provide the correct solution. On the back of this I have also
spotted something else that looks stupid in the cold light day, so will deal
with that as well (relates to these updates).