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

Ville Syrjälä
2014-03-20T15:19:33Z

On Thu, Mar 20, 2014 at 04:49:30PM +0200, Jani Nikula wrote:
> On Thu, 20 Mar 2014, Siva Chandra <sivachandra@google.com> wrote:
> > On Thu, Mar 20, 2014 at 6:25 AM, Jani Nikula
> > <jani.nikula@linux.intel.com> wrote:
> >> On Thu, 20 Mar 2014, Siva Chandra <sivachandra@google.com> wrote:
> >>> On Thu, Mar 20, 2014 at 3:52 AM, Jani Nikula
> >>> <jani.nikula@linux.intel.com> wrote:
> >>>> If this is for testing only, and the module parameter does not quite cut
> >>>> it, please add it to debugfs. That we can pretty much change at will.
> >>>
> >>> If I understand correctly, you are suggesting that the on/off knob
> >>> live in debugfs. So, should the module param in sysfs mirror this
> >>> debugfs knob?
> >>
> >> I guess the simplest thing to move forward would be something to update
> >> psr state after the module parameter has been changed, although it's
> >> perhaps a bit clumsy to use.
> >
> > Couldn't understand. May be an example to illustrate what you are saying?
>
> echo 1 > /sys/module/i915/parameters/enable_psr
> echo something > sys/kernel/debug/dri/0/i915_edp_psr_update
>
> where that debugfs file essentially calls intel_edp_psr_update() on
> update.
>
> I guess it could be i915_edp_psr_enable and echoing there would modify
> the module parameter and call update. With debugfs I'm not so fussy.

Whatever the interface I think it might be nice to allow you to force
the mode of PSR operation (main link off vs. standby).

--
Ville Syrjälä
Intel OTC