Re: [PATCH 07/14] drm/i915: Warn about want_panel_vdd in edp_panel_vdd_off_sync()

Jani Nikula
2014-08-19T13:37:10Z

On Tue, 19 Aug 2014, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> On Tue, Aug 19, 2014 at 10:36:52AM +0300, Jani Nikula wrote:
>> On Mon, 18 Aug 2014, ville.syrjala@linux.intel.com wrote:
>> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>> >
>> > If we force vdd off warn if someone is still using it. With this
>> > change the delayed vdd off work needs to check want_panel_vdd
>> > itself to make sure it doesn't try to turn vdd off when someone
>> > is using it.
>>
>> I think this calls for a prep cleanup patch to check and fix the uses of
>> edp_panel_vdd_off(intel_dp, true)
>> vs. edp_panel_vdd_off_sync(intel_dp). In particular, why are there
>> direct calls to the latter all over the place? Seems wrong.
>
> edp_panel_vdd_off() should always be paired with a edp_panel_vdd_on().
> If we were to call edp_panel_vdd_off() without the correct pairing we
> would get a warning due to want_panel_vdd==false, whereas
> edp_panel_vdd_off_sync() will now warn when want_panel_vdd==true.
> The direct calls to edp_panel_vdd_off_sync() are in places where we
> should not have want_panel_vdd==true (eg. system suspend) but we
> just want to force vdd off even if the delayed off work has alrady
> been scheduled.

Okay, care to add some of that as brief documentation comments for the
functions in question, as follow-up? IMO detailed kernel-docs here won't
be read by anyone and will just get stale.

BR,
Jani.

>
>>
>> BR,
>> Jani.
>>
>>
>> >
>> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
>> > ---
>> > drivers/gpu/drm/i915/intel_dp.c | 7 +++++--
>> > 1 file changed, 5 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
>> > index e6b4d4d..0fb510c 100644
>> > --- a/drivers/gpu/drm/i915/intel_dp.c
>> > +++ b/drivers/gpu/drm/i915/intel_dp.c
>> > @@ -1241,7 +1241,9 @@ static void edp_panel_vdd_off_sync(struct intel_dp *intel_dp)
>> >
>> > WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
>> >
>> > - if (intel_dp->want_panel_vdd || !edp_have_panel_vdd(intel_dp))
>> > + WARN_ON(intel_dp->want_panel_vdd);
>> > +
>> > + if (!edp_have_panel_vdd(intel_dp))
>> > return;
>> >
>> > DRM_DEBUG_KMS("Turning eDP VDD off\n");
>> > @@ -1273,7 +1275,8 @@ static void edp_panel_vdd_work(struct work_struct *__work)
>> > struct drm_device *dev = intel_dp_to_dev(intel_dp);
>> >
>> > drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
>> > - edp_panel_vdd_off_sync(intel_dp);
>> > + if (!intel_dp->want_panel_vdd)
>> > + edp_panel_vdd_off_sync(intel_dp);
>> > drm_modeset_unlock(&dev->mode_config.connection_mutex);
>> > }
>> >
>> > --
>> > 1.8.5.5
>> >
>> > _______________________________________________
>> > Intel-gfx mailing list
>> > Intel-gfx@lists.freedesktop.org
>> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>>
>> --
>> Jani Nikula, Intel Open Source Technology Center
>
> --
> Ville Syrjälä
> Intel OTC

--
Jani Nikula, Intel Open Source Technology Center