[alsa-devel] [PATCH] ASoC: Intel: Power down links before turning off display audio power

[Pierre-Louis Bossart]

On 6/22/18 4:25 AM, Sriram Periyasamy wrote:
> On certain platforms, Display HDMI HDA codec was not going to sleep state
> after the use when links are powered down after turning off the display
> power. As per the HW recommendation, links are powered down before turning
> off the display power to ensure that the codec goes to sleep state.

The change looks ok, I am still not clear on display power management. 
snd_hdac_display_power is called both from hdac_hdmi.c and skl.c in the 
respective probe/suspend/resume routines, wondering if this is redundant 
or intentional.

> 
> Signed-off-by: Sriram Periyasamy <sriramx.periyasamy at intel.com>
> Signed-off-by: Sanyog Kale <sanyog.r.kale at intel.com>
> ---
>   sound/soc/codecs/hdac_hdmi.c  | 12 +++++-------
>   sound/soc/intel/skylake/skl.c | 11 ++++++-----
>   2 files changed, 11 insertions(+), 12 deletions(-)
> 
> diff --git a/sound/soc/codecs/hdac_hdmi.c b/sound/soc/codecs/hdac_hdmi.c
> index 84f7a7a36e4b..b78fd84bf591 100644
> --- a/sound/soc/codecs/hdac_hdmi.c
> +++ b/sound/soc/codecs/hdac_hdmi.c
> @@ -2127,12 +2127,6 @@ static int hdac_hdmi_runtime_suspend(struct device *dev)
>   	 */
>   	snd_hdac_codec_read(hdev, hdev->afg, 0,	AC_VERB_SET_POWER_STATE,
>   							AC_PWRST_D3);
> -	err = snd_hdac_display_power(bus, false);
> -	if (err < 0) {
> -		dev_err(bus->dev, "Cannot turn on display power on i915\n");
> -		return err;
> -	}
> -
>   	hlink = snd_hdac_ext_bus_get_link(ebus, dev_name(dev));
>   	if (!hlink) {
>   		dev_err(dev, "hdac link not found\n");
> @@ -2141,7 +2135,11 @@ static int hdac_hdmi_runtime_suspend(struct device *dev)
>   
>   	snd_hdac_ext_bus_link_put(ebus, hlink);
>   
> -	return 0;
> +	err = snd_hdac_display_power(bus, false);
> +	if (err < 0)
> +		dev_err(bus->dev, "Cannot turn off display power on i915\n");
> +
> +	return err;
>   }
>   
>   static int hdac_hdmi_runtime_resume(struct device *dev)
> diff --git a/sound/soc/intel/skylake/skl.c b/sound/soc/intel/skylake/skl.c
> index 670ff9aaca55..c62e474717ff 100644
> --- a/sound/soc/intel/skylake/skl.c
> +++ b/sound/soc/intel/skylake/skl.c
> @@ -762,6 +762,12 @@ static void skl_probe_work(struct work_struct *work)
>   		}
>   	}
>   
> +	/*
> +	 * we are done probing so decrement link counts
> +	 */
> +	list_for_each_entry(hlink, &ebus->hlink_list, list)
> +		snd_hdac_ext_bus_link_put(ebus, hlink);
> +
>   	if (IS_ENABLED(CONFIG_SND_SOC_HDAC_HDMI)) {
>   		err = snd_hdac_display_power(bus, false);
>   		if (err < 0) {
> @@ -771,11 +777,6 @@ static void skl_probe_work(struct work_struct *work)
>   		}
>   	}
>   
> -	/*
> -	 * we are done probing so decrement link counts
> -	 */
> -	list_for_each_entry(hlink, &ebus->hlink_list, list)
> -		snd_hdac_ext_bus_link_put(ebus, hlink);
>   
>   	/* configure PM */
>   	pm_runtime_put_noidle(bus->dev);
>