Re: [RFC] Reorganizing HD-audio driver code?

[Takashi Iwai <tiwai@suse.de>]

On Thu, 03 Jul 2025 16:52:10 +0200,
Amadeusz Sławiński wrote:
> 
> 
> 
> On 2025-07-03 16:43, Takashi Iwai wrote:
> > On Thu, 03 Jul 2025 16:32:51 +0200,
> > Takashi Iwai wrote:
> >> 
> >> On Thu, 03 Jul 2025 15:57:48 +0200,
> >> Amadeusz Sławiński wrote:
> >>> 
> >>> 
> >>> 
> >>> On 2025-07-03 15:38, Takashi Iwai wrote:
> >>>> On Thu, 03 Jul 2025 15:29:56 +0200,
> >>>> Amadeusz Sławiński wrote:
> >>>>> 
> >>>>> 
> >>>>> 
> >>>>> On 2025-07-02 16:53, Takashi Iwai wrote:
> >>>>>> On Sun, 29 Jun 2025 11:22:25 +0200,
> >>>>>> Takashi Iwai wrote:
> >>>>>>> 
> >>>>>>> On Fri, 27 Jun 2025 15:22:20 +0200,
> >>>>>>> Richard Fitzgerald wrote:
> >>>>>>>> 
> >>>>>>>> On 27/06/2025 1:04 pm, Takashi Iwai wrote:
> >>>>>>>>> Hi,
> >>>>>>>>> 
> >>>>>>>>> HD-audio driver is known to be quite messy in both file structures and
> >>>>>>>>> its design, but until now I haven't touched its files paths so much
> >>>>>>>>> because I set a higher priority for the easiness of backport to stable
> >>>>>>>>> kernels.  But, you can't leave garbages forever, it's been already
> >>>>>>>>> high time for a large clean up.
> >>>>>>>>> 
> >>>>>>>>> So I tried a quick code reorganization, and put the result in
> >>>>>>>>> test/hda-reorg branch of sound.git tree.
> >>>>>>>>>       https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git/log/?h=test/hda-reorg
> >>>>>>>>> 
> >>>>>>>>> The basic idea is to move the code from sound/pci/hda/* into different
> >>>>>>>>> subdirectories in sound/hda/ per functionality, as most of the stuff
> >>>>>>>>> are independent from PCI, but rather HD-audio bus specific.
> >>>>>>>>> 
> >>>>>>>> 
> >>>>>>>> This all seems reasonable to me. I always thought it strange that there
> >>>>>>>> is a sound/hda directory but most of the HDA support isn't in that
> >>>>>>>> directory.
> >>>>>>> 
> >>>>>>> Thanks for your review!
> >>>>>>> 
> >>>>>>> It's a long story: at the time of ASoC Intel HD-audio support, we
> >>>>>>> thought to implement more ASoC-friendly way of HD-audio controller and
> >>>>>>> codec drivers, e.g. adapting DAPM and others.  So we began with the
> >>>>>>> factoring out the HD-audio basic core stuff to the common directory
> >>>>>>> sound/hda/*, while keeping the rest legacy stuff almost as is.  But
> >>>>>>> ASoC implementation didn't fly in the end from various reasons, and
> >>>>>>> the legacy HD-audio stuff was good enough for the actual use cases;
> >>>>>>> it's too bit to fail, after all.
> >>>>>>> 
> >>>>>>>>> The Realtek codec is split further to smaller pieces (which was really
> >>>>>>>>> huge).
> >>>>>>>> 
> >>>>>>>> Yes, that file was very confusing having support and quirks for so many
> >>>>>>>> Realtek parts all in one file.
> >>>>>>>> 
> >>>>>>>>> The Cirrus and TI sub-codec drivers are moved to codecs/side-codecs
> >>>>>>>>> subdirectory:
> >>>>>>>> 
> >>>>>>>> That's ok
> >>>>>>>> 
> >>>>>>>>> They can be put to each own directory and drop the file name prefix,
> >>>>>>>>> if we want, too.  Let me know if Cirrus and TI people would like to
> >>>>>>>>> split to more subdirectories.
> >>>>>>>> 
> >>>>>>>> I don't mind either way.
> >>>>>>>> The hda_component* files are common to the amps and the realtek driver
> >>>>>>>> so I wonder whether they belong in helpers. They are only utility
> >>>>>>>> wrappers around the kernel component-binding APIs.
> >>>>>>> 
> >>>>>>> Right.  So far, just because it's basically only binding with
> >>>>>>> side-codecs, I put into side-codecs subdirectory.
> >>>>>>> 
> >>>>>>>>> *HOWEVER* the biggest question is: whether it's worth?
> >>>>>>>>> 
> >>>>>>>>> Essentially, this makes almost impossible to make a patch for stable
> >>>>>>>>> trees from the original commit as is; one has to translate the file
> >>>>>>>>> paths and adjust manually in each patch.
> >>>>>>>> 
> >>>>>>>> Depends which file you are patching and how much it has changed.
> >>>>>>>> Git can figure out file renames (and changing directory is a rename).
> >>>>>>> 
> >>>>>>> I'm afraid that the Realtek codec changes might be hard to track
> >>>>>>> automatically.  Maybe the Cirrus side-codecs stuff would work.
> >>>>>>> 
> >>>>>>>>> Also, of course, if anyone is working on HD-audio stuff right now, the
> >>>>>>>>> work had to be adjusted to the new file path.  It'd be one-off action,
> >>>>>>>>> though.
> >>>>>>>> 
> >>>>>>>> Speaking only for Cirrus, I don't think this makes much extra effort
> >>>>>>>> for us. Our amp drivers have only changed location, so that should be
> >>>>>>>> trivial. The other file we change is patch_realtek.c but that typically
> >>>>>>>> is only 1-line quirk entries.
> >>>>>>> 
> >>>>>>> OK, thanks for confirmation!
> >>>>>> 
> >>>>>> ... and now I worked further on this, resulting in larger set of
> >>>>>> changes.  It's not only the file location changes but also the
> >>>>>> HD-audio codec driver binding changes.  So I put more people to Cc for
> >>>>>> catch their cautions.
> >>>>>> 
> >>>>>> To recap:
> >>>>>> 
> >>>>>> - The all HD-audio driver code are moved under sound/hda.
> >>>>>> 
> >>>>>>      % ls sound/hda
> >>>>>>      codecs/  common/  controllers/  core/  Kconfig  Makefile
> >>>>>> 
> >>>>>>      * The former hda core code is found in sound/hda/core.
> >>>>>>      * The former snd-hda-codec code is found in sound/hda/common.
> >>>>>>      * The former snd-hda-intel, tegra and acpi are put in
> >>>>>>        sound/hda/controllers.
> >>>>>>      * The former patch_* and co are put to sound/hda/codecs.
> >>>>>>      * Realtek codec driver is split to several modules as
> >>>>>>        sound/hda/codecs/realtek/alc*.
> >>>>>>      * Cirrus codec driver is split to cs420x and cs421x, put under
> >>>>>>        sound/hda/codecs/cirrus together with cs8409.
> >>>>>>      * HDMI codec driver is split to several modules under
> >>>>>>        sound/hda/codecs/hdmi
> >>>>>>      * Cirrus and TI sub-codecs are put under
> >>>>>>        sound/hda/codecs/side-codecs
> >>>>>> 
> >>>>>> - The HD-audio codec driver binding is changed from the embedded
> >>>>>>      hda_codec.patch_ops to hda_codec_driver.ops.
> >>>>>>      (As of now, hda_codec_driver.ops is a pointer, but it can be
> >>>>>>       embedded later, too.)
> >>>>>> 
> >>>>>>      This change required some code to be modified without the dynamic
> >>>>>>      override of callbacks.
> >>>>>> 
> >>>>>> - In future, we may convert the runtime PM handling to use the
> >>>>>>      standard pm_ops, too.  This was raised some time ago during the
> >>>>>>      discussion with Realtek devs.
> >>>>>> 
> >>>>>> The current patches are found in test/hda-reorg branch of sound git
> >>>>>> tree:
> >>>>>>      https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git/log/?h=test/hda-reorg
> >>>>>> 
> >>>>>> It's based on master branch for taking all changes of for-linus and
> >>>>>> for-next, hence the branch may be still frequently rebased.
> >>>>>> 
> >>>>>> So, please let me know if you see any issues or suggestions for this
> >>>>>> conversion.  I have no concrete plan for merging, but if everything
> >>>>>> looks fine, it can be even on the next 6.17, too.
> >>>>>> 
> >>>>> 
> >>>>> I've built it and put it on one of our machines and hit KASAN during
> >>>>> HDMI initialization, when I go back to master branch it works, so it
> >>>>> is something on test/hda-reorg.
> >>>> 
> >>>> Yes, there was bug in my branch that I fixed in this morning.
> >>>> Could you try the latest test/hda-reorg branch, commit
> >>>> 6491d5b2e256a678b3a138500bf601c916d3913e
> >>>> ?
> >>>> 
> >>> 
> >>> Still broken :(
> >> 
> >> OK, thanks for confirmation.
> >> 
> >> I guess it's a power up code path that happens just before the codec
> >> driver initialization.
> >> 
> >> Could you check whether the patch below covers it?
> This one works.
> 
> > A possible alternative is like below.  This one might be safer.
> > Let me know if either of them can work for you.
> 
> This one doesn't.

Interesting.  So the device_is_bound() returns true if it's called
during the binding operation.

> I will run more tests on the working one tomorrow, unless you want to
> try something else.

Thanks!


Takashi