[alsa-devel] [PATCH v2] ASoC: codec: hdac_hdmi add device_link to card device

[Pierre-Louis Bossart]

On 4/16/19 5:23 AM, Takashi Iwai wrote:
> On Sat, 13 Apr 2019 15:18:12 +0200,
> libin.yang at intel.com wrote:
>>
>> From: Libin Yang <libin.yang at intel.com>
>>
>> In resume from S3, HDAC HDMI codec driver dapm event callback may be
>> operated before HDMI codec driver turns on the display audio power
>> domain because of the contest between display driver and hdmi codec driver.
>>
>> This patch adds the device_link between soc card device (consumer) and
>> hdmi codec device (supplier) to make sure the sequence is always correct.
>>
>> Signed-off-by: Libin Yang <libin.yang at intel.com>
> 
> Reviewed-by: Takashi Iwai <tiwai at suse.de>
> 
> Is it an issue that has been present for older released kernels?
> If so, it deserves for Cc-to-stable.

Yes and no. In theory the same problem impacts the Skylake driver. 
However its support for HDMI has been flaky at best, see e.g. the 
probe/timing issues on Linus' laptop and a variety of devices in 
December, and the only real distribution using it - ChromeOS - does not 
resume from S3. Not to mention that products typically use 3.18 to 4.9.