Re: [PATCH] ASoC: Intel: Unify HDAudio-ext bus initialization

[Cezary Rojewski <cezary.rojewski@intel.com>]

On 2021-10-19 6:58 PM, Pierre-Louis Bossart wrote:
>>> hmm. It's not clear whether we should initialize the regular hdac_bus
>>> fields in the ext_bus_init(). For plain HDA, these are also initialized
>>> in the caller. E.g. in sound/pci/hda/hda_controller.c.
>>>
>>> So if we start cleaning up, should we go further put this in
>>> snd_hdac_bus_init()?
>>>
>>> Then another is what is the right place for settings like "sync_write =
>>> 1". While this settings applies to all current users of the extended
>>> bus, this is really hw specific setting and not really a property of
>>> the extended bus, so this feels a bit out-of-place.
>>
>> I'm rather in favor of bigger cleanups. We can definitely move further
>> in the future : )
> 
> I am not opposed to updates in this hdaudio-ext part, but I am in favor
> of less ambitious step-by-step changes.
> 
> a) This is legacy code where the initial authors have moved on, and it's
> very hard to figure out what the intent was. It's quite common to have
> discussion on feature v. bug, see e.g. the discussion we had on this in
> https://github.com/thesofproject/linux/pull/3175#pullrequestreview-772674119
> 
> b) In addition, this code is shared between two teams with separate
> testing/CI capabilities and limited number of commercial/shipping
> devices. There is a very large risk of introducing bugs even with the
> best intentions.
> 
> Before we do any changes in functionality, there are already basic steps
> that can be done, e.g. using consistent naming between variables, the
> existing code is just confusing as can be:
> 
> struct hdac_stream *stream;
> struct hdac_ext_stream *stream;
> struct hdac_stream *hstream;
> struct hdac_ext_stream *hstream;
> 
> I started basic cleanups here:
> https://github.com/thesofproject/linux/pull/3158, I haven't had time to
> complete this because of more important locking issues, but I intend to
> send those clarifications for the next cycle.
> 
> Again before we do large changes let's think of smaller steps and how we
> are going to validate those changes.

Agree, step-by-step is the way to go.

Isn't this patch a 'step' though? This isn't remotely a refactor, just 
gathering of common parts of ext-bus initialization. We could start with 
this so legacy users are unaffected, then have snd_hdac_bus_init() 
updated so snd_hdac_ext_bus_init() is devoid of 'core' fields 
assignments as suggested by Kai.


Regards,
Czarek