[alsa-devel] [RFC PATCH] ALSA: hda - Keep power link on for PantherPoint HDMI

[Takashi Iwai]

At Wed,  7 Nov 2012 09:22:33 +0100,
David Henningsson wrote:
> 
> On some of the PantherPoint HDMI machines we currently enable, we're seeing
> trouble with unsol events, i e detecting monitor presence, especially when
> on battery and after suspend/resume.
> 
> BugLink: https://bugs.launchpad.net/bugs/1075882
> Tested-by: Cyrus Lien <cyrus.lien at canonical.com>
> Signed-off-by: David Henningsson <david.henningsson at canonical.com>
> ---
>  sound/pci/hda/patch_hdmi.c |    8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> So far this is the workaround we have found to be working. Sometimes, it also
> seems that "cat /proc/asound/cardx/codec#x" can also make the HDMI unsol event
> trigger, so that the problem fixes itself.
> 
> We have not run any battery life tests to see if this causes more power consumption.

Looks safe at least, so I applied to for-next branch to give more
testing.  If you find a better solution, let me know.


thanks,

Takashi

> 
> diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
> index 39ca100..3155267 100644
> --- a/sound/pci/hda/patch_hdmi.c
> +++ b/sound/pci/hda/patch_hdmi.c
> @@ -1288,13 +1288,17 @@ static int hdmi_parse_codec(struct hda_codec *codec)
>  		}
>  	}
>  
> +#ifdef CONFIG_PM
> +	/* We're seeing some problems with unsolicited hot plug events on
> +	 * PantherPoint after S3, if this is not enabled */
> +	if (codec->vendor_id == 0x80862806)
> +		codec->bus->power_keep_link_on = 1;
>  	/*
>  	 * G45/IbexPeak don't support EPSS: the unsolicited pin hot plug event
>  	 * can be lost and presence sense verb will become inaccurate if the
>  	 * HDA link is powered off at hot plug or hw initialization time.
>  	 */
> -#ifdef CONFIG_PM
> -	if (!(snd_hda_param_read(codec, codec->afg, AC_PAR_POWER_STATE) &
> +	else if (!(snd_hda_param_read(codec, codec->afg, AC_PAR_POWER_STATE) &
>  	      AC_PWRST_EPSS))
>  		codec->bus->power_keep_link_on = 1;
>  #endif
> -- 
> 1.7.9.5
>