Re: [Intel-gfx] [PATCH 03/14] drm/i915: Get rid of the "sizes are 0 based" stuff

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Dec 01, 2021 at 05:18:54PM +0000, Souza, Jose wrote:
> On Wed, 2021-12-01 at 17:25 +0200, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Replace the "sizes are 0 based" stuff with just straight
> > up -1 where needed. Less confusing all around.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_sprite.c   | 26 ++++---------------
> >  .../drm/i915/display/skl_universal_plane.c    |  6 +----
> >  2 files changed, 6 insertions(+), 26 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_sprite.c b/drivers/gpu/drm/i915/display/intel_sprite.c
> > index 1b99a9501a45..2067a7bca4a8 100644
> > --- a/drivers/gpu/drm/i915/display/intel_sprite.c
> > +++ b/drivers/gpu/drm/i915/display/intel_sprite.c
> > @@ -431,10 +431,6 @@ vlv_sprite_update_noarm(struct intel_plane *plane,
> >  	u32 crtc_h = drm_rect_height(&plane_state->uapi.dst);
> >  	unsigned long irqflags;
> >  
> > -	/* Sizes are 0 based */
> 
> In my opinion at least this comment should stay, helps understand why the -1. 

It's just normal practice for almost all such registers.
We don't have similar comments elsewhere either. Also if 
the code already says "foo-1" then I don't see what extra
the comment gets you.

> 
> > -	crtc_w--;
> > -	crtc_h--;
> > -
> >  	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
> >  
> >  	intel_de_write_fw(dev_priv, SPSTRIDE(pipe, plane_id),
> > @@ -442,7 +438,7 @@ vlv_sprite_update_noarm(struct intel_plane *plane,
> >  	intel_de_write_fw(dev_priv, SPPOS(pipe, plane_id),
> >  			  (crtc_y << 16) | crtc_x);
> >  	intel_de_write_fw(dev_priv, SPSIZE(pipe, plane_id),
> > -			  (crtc_h << 16) | crtc_w);
> > +			  ((crtc_h - 1) << 16) | (crtc_w - 1));
> >  
> >  	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
> >  }
> > @@ -866,21 +862,15 @@ ivb_sprite_update_noarm(struct intel_plane *plane,
> >  	u32 sprscale = 0;
> >  	unsigned long irqflags;
> >  
> > -	/* Sizes are 0 based */
> > -	src_w--;
> > -	src_h--;
> > -	crtc_w--;
> > -	crtc_h--;
> > -
> >  	if (crtc_w != src_w || crtc_h != src_h)
> > -		sprscale = SPRITE_SCALE_ENABLE | (src_w << 16) | src_h;
> > +		sprscale = SPRITE_SCALE_ENABLE | ((src_w - 1) << 16) | (src_h - 1);
> >  
> >  	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
> >  
> >  	intel_de_write_fw(dev_priv, SPRSTRIDE(pipe),
> >  			  plane_state->view.color_plane[0].mapping_stride);
> >  	intel_de_write_fw(dev_priv, SPRPOS(pipe), (crtc_y << 16) | crtc_x);
> > -	intel_de_write_fw(dev_priv, SPRSIZE(pipe), (crtc_h << 16) | crtc_w);
> > +	intel_de_write_fw(dev_priv, SPRSIZE(pipe), ((crtc_h - 1) << 16) | (crtc_w - 1));
> >  	if (IS_IVYBRIDGE(dev_priv))
> >  		intel_de_write_fw(dev_priv, SPRSCALE(pipe), sprscale);
> >  
> > @@ -1208,21 +1198,15 @@ g4x_sprite_update_noarm(struct intel_plane *plane,
> >  	u32 dvsscale = 0;
> >  	unsigned long irqflags;
> >  
> > -	/* Sizes are 0 based */
> > -	src_w--;
> > -	src_h--;
> > -	crtc_w--;
> > -	crtc_h--;
> > -
> >  	if (crtc_w != src_w || crtc_h != src_h)
> > -		dvsscale = DVS_SCALE_ENABLE | (src_w << 16) | src_h;
> > +		dvsscale = DVS_SCALE_ENABLE | ((src_w - 1) << 16) | (src_h - 1);
> >  
> >  	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
> >  
> >  	intel_de_write_fw(dev_priv, DVSSTRIDE(pipe),
> >  			  plane_state->view.color_plane[0].mapping_stride);
> >  	intel_de_write_fw(dev_priv, DVSPOS(pipe), (crtc_y << 16) | crtc_x);
> > -	intel_de_write_fw(dev_priv, DVSSIZE(pipe), (crtc_h << 16) | crtc_w);
> > +	intel_de_write_fw(dev_priv, DVSSIZE(pipe), ((crtc_h - 1) << 16) | (crtc_w - 1));
> >  	intel_de_write_fw(dev_priv, DVSSCALE(pipe), dvsscale);
> >  
> >  	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
> > diff --git a/drivers/gpu/drm/i915/display/skl_universal_plane.c b/drivers/gpu/drm/i915/display/skl_universal_plane.c
> > index 9ff24a0e79b4..09948922016b 100644
> > --- a/drivers/gpu/drm/i915/display/skl_universal_plane.c
> > +++ b/drivers/gpu/drm/i915/display/skl_universal_plane.c
> > @@ -1022,10 +1022,6 @@ skl_program_plane_noarm(struct intel_plane *plane,
> >  	u32 src_h = drm_rect_height(&plane_state->uapi.src) >> 16;
> >  	unsigned long irqflags;
> >  
> > -	/* Sizes are 0 based */
> > -	src_w--;
> > -	src_h--;
> > -
> >  	/* The scaler will handle the output position */
> >  	if (plane_state->scaler_id >= 0) {
> >  		crtc_x = 0;
> > @@ -1045,7 +1041,7 @@ skl_program_plane_noarm(struct intel_plane *plane,
> >  	intel_de_write_fw(dev_priv, PLANE_POS(pipe, plane_id),
> >  			  (crtc_y << 16) | crtc_x);
> >  	intel_de_write_fw(dev_priv, PLANE_SIZE(pipe, plane_id),
> > -			  (src_h << 16) | src_w);
> > +			  ((src_h - 1) << 16) | (src_w - 1));
> >  
> >  	if (intel_fb_is_rc_ccs_cc_modifier(fb->modifier)) {
> >  		intel_de_write_fw(dev_priv, PLANE_CC_VAL(pipe, plane_id, 0),
> 

-- 
Ville Syrjälä
Intel