[alsa-devel] [PATCH] ALSA: hda - Fix Skylake codec timeouts

[Takashi Iwai]

On Wed, 15 Jul 2015 09:39:35 +0200,
David Henningsson wrote:
> 
> When the controller is powered up but the HDMI codec is powered down
> on Skylake, the power well is turned off. When the codec is then
> powered up again, we need to poke the codec a little extra to make
> sure it wakes up. Otherwise we'll get sad "no response from codec"
> messages and broken audio.
> 
> Signed-off-by: David Henningsson <david.henningsson at canonical.com>
> Tested-by: Woodrow Shen <woodrow.shen at canonical.com>
> ---
> 
>  * It would good to have an ack from Intel on this patch, since they
>    have better hardware knowledge than I.
> 
>  * Also I haven't really kept track of all recent reorganisation of the
>    hda driver so I'm not totally sure how many kernels back (if any)
>    that this applies to
> 
>  sound/pci/hda/hda_intel.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> index ca151b4..872e9a7 100644
> --- a/sound/pci/hda/hda_intel.c
> +++ b/sound/pci/hda/hda_intel.c
> @@ -567,9 +567,17 @@ static int azx_position_check(struct azx *chip, struct azx_dev *azx_dev)
>  /* Enable/disable i915 display power for the link */
>  static int azx_intel_link_power(struct azx *chip, bool enable)
>  {
> +	int err;
>  	struct hdac_bus *bus = azx_bus(chip);
>  
> -	return snd_hdac_display_power(bus, enable);
> +	err = snd_hdac_display_power(bus, enable);
> +	if (err < 0)
> +		return err;
> +	if (enable && (chip->driver_caps & AZX_DCAPS_I915_POWERWELL)) {
> +		snd_hdac_set_codec_wakeup(bus, true);
> +		snd_hdac_set_codec_wakeup(bus, false);
> +	}

Wouldn't it be better to put in snd_hadc_display_power() itself? 

--- a/sound/hda/hdac_i915.c
+++ b/sound/hda/hdac_i915.c
@@ -56,8 +56,11 @@ int snd_hdac_display_power(struct hdac_bus *bus, bool enable)
 		enable ? "enable" : "disable");
 
 	if (enable) {
-		if (!bus->i915_power_refcount++)
+		if (!bus->i915_power_refcount++) {
 			acomp->ops->get_power(acomp->dev);
+			snd_hdac_set_codec_wakeup(bus, true);
+			snd_hdac_set_codec_wakeup(bus, false);
+		}
 	} else {
 		WARN_ON(!bus->i915_power_refcount);
 		if (!--bus->i915_power_refcount)

Takashi