On 6/24/20 11:43 AM, Takashi Iwai wrote:
On Wed, 24 Jun 2020 17:33:45 +0200,
Pierre-Louis Bossart wrote:
The silent stream is enabled with a Kconfig option, as well as a kernel
parameter should there be a need to override the build time default.
I'm not sure whether the module option is the best interface.
An alternative is a mixer element that controls dynamically. Then
it'll be per card unlike the module option.
+1, kcontrol seems the appropriate way to control this.
It was my suggestion to use Kconfig+kernel parameter for
simplicity/overrides.
The kcontrol is a nice idea, but in practice we typically only have
one card dealing with HDMI.
Not really. There are systems with two HDMI outputs from both
integrated and discrete GPUs. Most modern systems are only with
hybrid graphics, though.
Ok, maybe I am mistaken, in most of the HDMI issues we've seen only one
HDMI source.
But it's a good point that this is only supposed to be used for Intel
whether it's a kernel parameter or a kcontrol shouldn't this be
dependent on a PCI ID being detected and a SKYLAKE flag being set? it's
my understanding that this applies from Skylake to TigerLake, not before.
It also doesn't have a UCM representation
so would force the use of amixer and manual configs, or the UCM file
would always set the mode.
But people usually use the distro kernels, so the situation is more or
less equivalent; you'd have to adjust a module option manually if you
want a different one from the default, and you'd have to be root to
change it.
So, rather the question is how we should provide the setup of such
parameter. It's supposed to be a part of power management stuff that
should be touched by either a smart PM tool or a manual override such
as runtime PM setup? Or can it be seen as a more casual tuning?
I am not aware of such tools. The only thing I know is that some of the
HDaudio power settings are already controlled by kernel parameters, e.g.
/etc/modprobe.d/audio_powersave.conf
options snd_hda_intel power_save=1
