[Intel-gfx] [PATCH 2/7] drm/i915: add DisplayPort amp unmute for LPE audio mode

[Ville Syrjälä]

On Thu, Feb 02, 2017 at 10:57:30AM +0100, Takashi Iwai wrote:
> On Tue, 31 Jan 2017 22:36:44 +0100,
> Takashi Iwai wrote:
> > 
> > From: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
> > 
> > Enable unmute/mute amp notification. This doesn't seem to affect
> > HDMI support so this is done unconditionally.
> > 
> > An earlier version of this patch set a chicken bit at address 0x62F38
> > prior to the mute/unmute but this register doesn't seem to do anything
> > so this phase was removed.
> 
> Sorry, this seems like a wrong result.  It worked yesterday, but when
> I retested the latest code today, it didn't work any longer.
> Then, after setting the chicken bit, it starts working again.
> 
> But now I can't make it broken again.  Turn off the monitor, turn off
> the machine, DPMS off, suspend/resume...  All still works without
> chicken bit set.
> 
> Also, the chicken bit of the register 0x62f38 couldn't be read back.
> The register always returns zero when read.

The docs do say it's write-only actually.

-- 
Ville Syrjälä
Intel OTC