[Intel-gfx] [PATCH 5/8] drm/i915: Check error return when converting pipe to connector

[Imre Deak]

On Wed, Apr 26, 2017 at 05:12:32PM +0300, Jani Nikula wrote:
> On Wed, 26 Apr 2017, Imre Deak <imre.deak at intel.com> wrote:
> > An error from intel_get_pipe_from_connector() would mean a bug somewhere
> > else, but we still should check for it to prevent some other more
> > obscure bug later.
> 
> Do check for invalid pipe, but please just limp on instead of bailing
> out of the functions. See notes inline.
> 
> BR,
> Jani.
> 
> >
> > Signed-off-by: Imre Deak <imre.deak at intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_panel.c | 14 ++++++++++++--
> >  1 file changed, 12 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> > index cb50c52..dbe05ec 100644
> > --- a/drivers/gpu/drm/i915/intel_panel.c
> > +++ b/drivers/gpu/drm/i915/intel_panel.c
> > @@ -888,10 +888,14 @@ static void pch_enable_backlight(struct intel_connector *connector)
> >  	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
> >  	struct intel_panel *panel = &connector->panel;
> >  	enum pipe pipe = intel_get_pipe_from_connector(connector);
> > -	enum transcoder cpu_transcoder =
> > -		intel_pipe_to_cpu_transcoder(dev_priv, pipe);
> > +	enum transcoder cpu_transcoder;
> >  	u32 cpu_ctl2, pch_ctl1, pch_ctl2;
> >  
> > +	if (WARN_ON_ONCE(pipe == INVALID_PIPE))
> > +		return;
> 
> Please just assign e.g. TRANSCODER_EDP to cpu_transcoder in this case,
> go on, and hope for the best. Do leave the warn in place though.
> 
> > +
> > +	cpu_transcoder = intel_pipe_to_cpu_transcoder(dev_priv, pipe);
> > +
> >  	cpu_ctl2 = I915_READ(BLC_PWM_CPU_CTL2);
> >  	if (cpu_ctl2 & BLM_PWM_ENABLE) {
> >  		DRM_DEBUG_KMS("cpu backlight already enabled\n");
> > @@ -973,6 +977,9 @@ static void i965_enable_backlight(struct intel_connector *connector)
> >  	enum pipe pipe = intel_get_pipe_from_connector(connector);
> >  	u32 ctl, ctl2, freq;
> >  
> > +	if (WARN_ON_ONCE(pipe == INVALID_PIPE))
> > +		return;
> 
> Same here, please just assign e.g. PIPE_A here with the warning, and
> limp on.
> 
> > +
> >  	ctl2 = I915_READ(BLC_PWM_CTL2);
> >  	if (ctl2 & BLM_PWM_ENABLE) {
> >  		DRM_DEBUG_KMS("backlight already enabled\n");
> > @@ -1093,6 +1100,9 @@ void intel_panel_enable_backlight(struct intel_connector *connector)
> >  	if (!panel->backlight.present)
> >  		return;
> >  
> > +	if (WARN_ON_ONCE(pipe == INVALID_PIPE))
> > +		return;
> 
> Here, pipe is only used for the debug logging, just skip that instead.

Ok, can do. This would make things inconsistent wrt.
vlv_enable/disable_backlight() though, so are you ok if I change those
too accordingly?

--Imre

> 
> > +
> >  	DRM_DEBUG_KMS("pipe %c\n", pipe_name(pipe));
> >  
> >  	mutex_lock(&dev_priv->backlight_lock);
> 
> -- 
> Jani Nikula, Intel Open Source Technology Center