[alsa-devel] [PATCH 02/10] ALSA: hda - Bind codecs via standard bus

[Lars-Peter Clausen]

On 02/28/2015 11:06 AM, Takashi Iwai wrote:
> At Sat, 28 Feb 2015 10:55:32 +0100,
> Lars-Peter Clausen wrote:
>>
>> On 02/26/2015 06:00 PM, Takashi Iwai wrote:
>>> Now we create the standard HD-audio bus (/sys/bus/hdaudio), and bind
>>> the codec driver with the codec device over there.  This is the first
>>> step of the whole transition so that the changes to each codec driver
>>> are kept as minimal as possible.
>>>
>>> Each codec driver needs to register hda_codec_driver struct containing
>>> the currently existing preset via the new helper macro
>>> module_hda_codec_driver().  The old hda_codec_preset_list is replaced
>>> with this infrastructure.  The generic parsers (for HDMI and other)
>>> are also included in the preset with the special IDs to bind
>>> uniquely.
>>>
>>> In HD-audio core side, the device binding code is split to
>>> hda_bind.c.  It provides the snd_hda_bus_type implementation to match
>>> the codec driver with the given codec vendor ID.  It also manages the
>>> module auto-loading by itself like before: when the matching isn't
>>> found, it tries to probe the corresponding codec modules, and finally
>>> falls back to the generic drivers.  (The special ID mentioned above is
>>> set at this stage.)
>>>
>>> The only visible change to outside is that the hdaudio sysfs entry now
>>> appears in /sys/bus/devices, not as a sound class device.
>>>
>>> More works to move the suspend/resume and remove ops will be
>>> (hopefully) done in later patches.
>>
>> Great stuff. AC'97 is next? ;)
>
> Feel free to join to the club 97! :)
>
>> [...]
>>> +	drv->driver.probe = hda_codec_driver_probe;
>>> +	drv->driver.remove = hda_codec_driver_remove;
>>
>> Small nitpick, in my opinion it would be cleaner to use the snd_hda_bus_type
>> probe/remove callbacks for this.
>
> Correct.  However, this would need more changes.  In this series, I'm
> trying a gradual transition without a big surprise.  The merit of this
> patch is that you need minimum changes in the codec driver side.

What I meant was instead of dynamically assigning the probe/remove callbacks 
of each driver struct, just statistically setup the probe/remove callbacks 
for the bus_type with the same callbacks. From a functional point of view 
there should not be any difference.

- Lars