[Intel-gfx] [PATCH] drm/i915/cnl: Add information to missing case.

[Vivi, Rodrigo]

On Fri, 2017-06-16 at 21:54 +0000, Navare, Manasi D wrote:
> On Fri, 2017-06-16 at 21:26 +0000, Vivi, Rodrigo wrote:
> > On Fri, 2017-06-16 at 21:21 +0000, Pandiyan, Dhinakaran wrote:
> > > On Fri, 2017-06-16 at 14:12 -0700, Manasi Navare wrote:
> > > > On Fri, Jun 16, 2017 at 08:58:25PM +0000, Pandiyan, Dhinakaran wrote:
> > > > > On Fri, 2017-06-16 at 13:20 -0700, Rodrigo Vivi wrote:
> > > > > > This missing case could be reached out on missing type or 
> > > > > > missing voltage.
> > > > > 
> > > > > Should we even reach this far with a missing DDI type?
> > > > > 
> > > > > -DK
> > > > >
> > > > 
> > > > Yes it is possible that we get into this situation if reading of 
> > > > the vccio voltage from PORT_COMP_DW3 returns a garbage value due 
> > > > to some corruption
> > > 
> > > MISSING_CASE already logs that.
> > > 
> > > > or lets say the type is something that is not supported on this 
> > > > platform.
> > > > 
> > > But my question is, should we even be trying to program vswing 
> > > without knowing the ddi type or for an invalid type?
> > 
> > we will reach the return; and avoid vswing programming.
> > And logs will give us some information of what failed during modeset.
> > 
> 
> Correct me if I am wrong, the only callers I could see are
> intel_dp_set_signal_levels() and intel_ddi_pre_enable_hdmi(). In both cases, the encoder type should have been set appropriately. My concern is that if we are seeing some other type, we should be handling that before calling cnl_ddi_vswing_program()

this is why I didn't get the missing case on the type if/else ;)

we should never reach that case, but in case there is the missing case
an extra debug message doesn't hurt...

> 
> 
> But this debug message catches the condition where the type is correct but the type and corresponding vccio voltage
> Combination is wrong and the ddi tables are not present for that combination.
> I definitely think it is a good idea to have this Debug print here in the missing case.
> 
> Manasi
> 
> > > 
> > > > 
> > > > > >  So let's add a debug
> > > > > > message to make our lives easier whenever this might happen.
> > > > > > 
> > > > > > Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
> > > > > > Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> > > > > > ---
> > > > > >  drivers/gpu/drm/i915/intel_ddi.c | 1 +
> > > > > >  1 file changed, 1 insertion(+)
> > > > > > 
> > > > > > diff --git a/drivers/gpu/drm/i915/intel_ddi.c 
> > > > > > b/drivers/gpu/drm/i915/intel_ddi.c
> > > > > > index e66947a..c96c8d0 100644
> > > > > > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > > > > > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > > > > > @@ -1802,6 +1802,7 @@ static void cnl_ddi_vswing_program(struct drm_i915_private *dev_priv,
> > > > > >  	}
> > > > > >  
> > > > > >  	if (ddi_translations == NULL) {
> > > > > > +		DRM_DEBUG_KMS("Missing DDI translation table for type %d 
> > > > > > +with voltage %d\n", type, voltage);
> > > > > >  		MISSING_CASE(voltage);
> > > > > >  		return;
> > > > > >  	}
> > > > 
> > > > Like Paulo suggested it would be better to use a switch statement 
> > > > for different vccio voltages and then have this in the default. What do you think?
> > 
> > we don't need to iterate on voltages... and the switch for type 
> > wouldn't catch failures happening inside the functions where we 
> > actually pick the table.
> > 
> > > > 
> > > > Manasi
> > > > 
> > > > 
> > > > > 
> > > > > _______________________________________________
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> > 
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