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

[Takashi Iwai]

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.


thanks,

Takashi

> ---
>  sound/soc/codecs/hdac_hdmi.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/sound/soc/codecs/hdac_hdmi.c b/sound/soc/codecs/hdac_hdmi.c
> index 5eeb0fe..4de1fbf 100644
> --- a/sound/soc/codecs/hdac_hdmi.c
> +++ b/sound/soc/codecs/hdac_hdmi.c
> @@ -1855,6 +1855,17 @@ static int hdmi_codec_probe(struct snd_soc_component *component)
>  	hdmi->card = dapm->card->snd_card;
>  
>  	/*
> +	 * Setup a device_link between card device and HDMI codec device.
> +	 * The card device is the consumer and the HDMI codec device is
> +	 * the supplier. With this setting, we can make sure that the audio
> +	 * domain in display power will be always turned on before operating
> +	 * on the HDMI audio codec registers.
> +	 * Let's use the flag DL_FLAG_AUTOREMOVE_CONSUMER. This can make
> +	 * sure the device link is freed when the machine driver is removed.
> +	 */
> +	device_link_add(component->card->dev, &hdev->dev, DL_FLAG_RPM_ACTIVE |
> +			DL_FLAG_AUTOREMOVE_CONSUMER);
> +	/*
>  	 * hdac_device core already sets the state to active and calls
>  	 * get_noresume. So enable runtime and set the device to suspend.
>  	 */
> -- 
> 2.7.4
>