Re: [PATCH] drm/i915: Add a DRM property "psr"

Damien Lespiau
2014-03-19T15:06:26Z

On Wed, Mar 19, 2014 at 09:44:38AM +0100, Daniel Vetter wrote:
> On Tue, Mar 18, 2014 at 01:53:56PM -0700, Siva Chandra wrote:
> > On Tue, Mar 18, 2014 at 1:06 PM, Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
> > > On Tue, 18 Mar 2014 12:51:07 -0700
> > > Siva Chandra <sivachandra@chromium.org> wrote:
> > >
> > >> This property helps one turn PSR "on" and "off" via xrandr.
> > >> The default value is same as that of the module param i915.enable_psr.
> > >>
> > >> Signed-off-by: Siva Chandra <sivachandra@google.com>
> > >> ---
> > >
> > > So are you using this in Chromium for disabling PSR in cases where it
> > > doesn't work? Or to optimize power consumption when the kernel driver
> > > gets it wrong? Or just for debug?
> >
> > We are testing a few PSR panels; Having a knob to turn PSR on and off
> > would be of great convenience for manual testing and for test scripts.
>
> Is the module param not good enough for that? Iirc we recheck that every
> time ...

(the module parameter is accessible through a file in sysfs:
/sys/module/i915/parameters/enable_psr)

Alternatively, doesn't it look like something that belongs to debugfs?
ie not an API with a stability guarantee?

--
Damien