Re: [PATCH 4/6] drm/i915: Cleanup if the EDP transcoder has a bobug input value

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Mar 22, 2013 at 06:34:43PM -0300, Paulo Zanoni wrote:
> Hi
> 
> 2013/3/7 Damien Lespiau <damien.lespiau@intel.com>:
> > In the case where the hardware has been wrongly programmed and the EDP
> > TRANS_DDI_FUNC_CTL register has a bogus value in its EDP Input field, we
> > were using the pipe variable uninitialized.
> >
> > In this case, shutdown the transcoder. It will be programmed correctly
> > the next time we try to enabled eDP.
> >
> > Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_display.c |    8 ++++++++
> >  1 files changed, 8 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 502cb28..875baf1 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -9107,6 +9107,13 @@ void intel_modeset_setup_hw_state(struct drm_device *dev,
> >                         case TRANS_DDI_EDP_INPUT_C_ONOFF:
> >                                 pipe = PIPE_C;
> >                                 break;
> > +                       default:
> > +                               /* A bogus value has been programmed, disable
> > +                                * the transcoder */
> > +                               WARN(1, "Bogus eDP source %08x\n", tmp);
> > +                               intel_ddi_disable_transcoder_func(dev_priv,
> > +                                               TRANSCODER_EDP);
> 
> I imagine this patch is a result of checking some code analyzer and
> not real hardware, so we didn't really test this code on real
> hardware, right? The WARN is definitely a must-have, but I kinda fear
> this "disable" code since we can easily freeze the machine if we get
> the mode set sequence wrong. Anyway, if the hardware is programmed in
> an inconsistent way I don't really think there's a "right way" to
> disable it, so:
> 
> Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Queued for -next, thanks for the patch.

> But we need to watch out in case users start reporting about machines
> that freeze during boot.

And added a little note to the patch to this effect.
-Daniel
> 
> > +                               goto setup_pipes;
> >                         }
> >
> >                         crtc = to_intel_crtc(dev_priv->pipe_to_crtc_mapping[pipe]);
> > @@ -9117,6 +9124,7 @@ void intel_modeset_setup_hw_state(struct drm_device *dev,
> >                 }
> >         }
> >
> > +setup_pipes:
> >         for_each_pipe(pipe) {
> >                 crtc = to_intel_crtc(dev_priv->pipe_to_crtc_mapping[pipe]);
> >
> > --
> > 1.7.7.5
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> 
> 
> -- 
> Paulo Zanoni
> _______________________________________________
> 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