[Intel-gfx] [PATCH] drm/i915: Kill the remaining CHV HBR2 leftovers

[Pandiyan, Dhinakaran]

On Thu, 2018-03-08 at 14:58 +0200, Ville Syrjälä wrote:
> On Wed, Mar 07, 2018 at 09:41:06PM +0000, Pandiyan, Dhinakaran wrote:
> > 
> > 
> > 
> > On Fri, 2018-03-02 at 11:56 +0200, Ville Syrjala wrote:
> > > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > 
> > > AFAIK CHV was supposed to have HBR2 originally, but in the end the feature
> > > was dropped. We still have some code leftovers from those early days.
> > > Eliminate them.
> > > 
> > 
> > Not much in the spec about HBR2 other than the support for TP3. Since we
> > don't support HBR2 on CHV, removing the unused TPS3 bits looks correct.
> > 
> > 
> > 
> > > The extra bit for the training pattern seems to be dead in the hardware.
> > > I can set it (in fact I can set almost any reserved bit in the
> > > registers) but it doesn't seem to interfere with the operation of the
> > > hardware. Either that or I'm very lucky that my displays complete link
> > > training with the incorrect pattern being sent out.
> > > 
> > 
> > I don't think I follow this, are you saying there's no need to clear the
> > TPS3 bit? Isn't it better to have the mask include 1 << 14, so that
> > _intel_dp_set_link_train() clears the bit?
> 
> I'm saying the bit doesn't actually seem to exist in hardware. In fact
> most of my specs don't list it either. Looks like only the "K0" specs
> have it.
> 

Thanks for clarifying.

Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>

> > 
> > 
> > 
> > > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/i915_reg.h |  2 --
> > >  drivers/gpu/drm/i915/intel_dp.c | 20 ++++----------------
> > >  2 files changed, 4 insertions(+), 18 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > > index 95a2e51ecbb0..f3efc242df2d 100644
> > > --- a/drivers/gpu/drm/i915/i915_reg.h
> > > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > > @@ -5250,8 +5250,6 @@ enum {
> > >  #define   DP_LINK_TRAIN_OFF		(3 << 28)
> > >  #define   DP_LINK_TRAIN_MASK		(3 << 28)
> > >  #define   DP_LINK_TRAIN_SHIFT		28
> > > -#define   DP_LINK_TRAIN_PAT_3_CHV	(1 << 14)
> > > -#define   DP_LINK_TRAIN_MASK_CHV	((3 << 28)|(1<<14))
> > >  
> > >  /* CPT Link training mode */
> > >  #define   DP_LINK_TRAIN_PAT_1_CPT	(0 << 8)
> > > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > > index aba2f45819d8..df1772044208 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > > @@ -92,8 +92,6 @@ static const struct dp_link_dpll chv_dpll[] = {
> > >  		{ .p1 = 4, .p2 = 2, .n = 1, .m1 = 2, .m2 = 0x819999a } },
> > >  	{ 270000,	/* m2_int = 27, m2_fraction = 0 */
> > >  		{ .p1 = 4, .p2 = 1, .n = 1, .m1 = 2, .m2 = 0x6c00000 } },
> > > -	{ 540000,	/* m2_int = 27, m2_fraction = 0 */
> > > -		{ .p1 = 2, .p2 = 1, .n = 1, .m1 = 2, .m2 = 0x6c00000 } }
> > >  };
> > >  
> > >  /**
> > > @@ -2908,10 +2906,7 @@ _intel_dp_set_link_train(struct intel_dp *intel_dp,
> > >  		}
> > >  
> > >  	} else {
> > > -		if (IS_CHERRYVIEW(dev_priv))
> > > -			*DP &= ~DP_LINK_TRAIN_MASK_CHV;
> > > -		else
> > > -			*DP &= ~DP_LINK_TRAIN_MASK;
> > > +		*DP &= ~DP_LINK_TRAIN_MASK;
> > >  
> > >  		switch (dp_train_pat & DP_TRAINING_PATTERN_MASK) {
> > >  		case DP_TRAINING_PATTERN_DISABLE:
> > > @@ -2924,12 +2919,8 @@ _intel_dp_set_link_train(struct intel_dp *intel_dp,
> > >  			*DP |= DP_LINK_TRAIN_PAT_2;
> > >  			break;
> > >  		case DP_TRAINING_PATTERN_3:
> > > -			if (IS_CHERRYVIEW(dev_priv)) {
> > > -				*DP |= DP_LINK_TRAIN_PAT_3_CHV;
> > > -			} else {
> > > -				DRM_DEBUG_KMS("TPS3 not supported, using TPS2 instead\n");
> > > -				*DP |= DP_LINK_TRAIN_PAT_2;
> > > -			}
> > > +			DRM_DEBUG_KMS("TPS3 not supported, using TPS2 instead\n");
> > > +			*DP |= DP_LINK_TRAIN_PAT_2;
> > >  			break;
> > >  		}
> > >  	}
> > > @@ -3668,10 +3659,7 @@ intel_dp_link_down(struct intel_encoder *encoder,
> > >  		DP &= ~DP_LINK_TRAIN_MASK_CPT;
> > >  		DP |= DP_LINK_TRAIN_PAT_IDLE_CPT;
> > >  	} else {
> > > -		if (IS_CHERRYVIEW(dev_priv))
> > > -			DP &= ~DP_LINK_TRAIN_MASK_CHV;
> > > -		else
> > > -			DP &= ~DP_LINK_TRAIN_MASK;
> > > +		DP &= ~DP_LINK_TRAIN_MASK;
> > >  		DP |= DP_LINK_TRAIN_PAT_IDLE;
> > >  	}
> > >  	I915_WRITE(intel_dp->output_reg, DP);
>