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

Daniel Vetter
2014-08-26T09:21:08Z

On Tue, Aug 19, 2014 at 04:37:03PM +0300, Jani Nikula wrote:
> 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.

Hm, imo a wrappe for vdd_off_sync or would be clearer than piles of
comments. Or maybe just vdd_sync, akin to all the work/time _sync
functions. Our system suspend/resume code is splattered with such
functions, so the code pattern should be clear with just that.

Perhaps as a follow-up patch on top of all of this?
-Daniel

>
> 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
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch