Re: [PATCH 01/14] drm/i915: Nuke posting reads from plane update/disable funcs

From: Rodrigo Vivi <rodrigo.vivi@intel.com>
To: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 01/14] drm/i915: Nuke posting reads from plane update/disable funcs
Date: Thu, 1 Nov 2018 11:08:46 -0700	[thread overview]
Message-ID: <20181101180846.GB2092@intel.com> (raw)
In-Reply-To: <20181101150605.18235-2-ville.syrjala@linux.intel.com>

On Thu, Nov 01, 2018 at 05:05:52PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> No need for the posting reads in the plane update/disable hooks.
> If we need a posting read for something then a single one at the
> very end would be sufficient. We have that anyway in the form
> of eg. scanline/frame counter reads.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

> ---
>  drivers/gpu/drm/i915/intel_display.c |  6 ------
>  drivers/gpu/drm/i915/intel_sprite.c  | 12 ------------
>  2 files changed, 18 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 7e1131d806ae..c5ce3892d583 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -3378,7 +3378,6 @@ static void i9xx_update_plane(struct intel_plane *plane,
>  			      intel_plane_ggtt_offset(plane_state) +
>  			      dspaddr_offset);
>  	}
> -	POSTING_READ_FW(reg);
>  
>  	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>  }
> @@ -3397,7 +3396,6 @@ static void i9xx_disable_plane(struct intel_plane *plane,
>  		I915_WRITE_FW(DSPSURF(i9xx_plane), 0);
>  	else
>  		I915_WRITE_FW(DSPADDR(i9xx_plane), 0);
> -	POSTING_READ_FW(DSPCNTR(i9xx_plane));
>  
>  	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>  }
> @@ -9850,8 +9848,6 @@ static void i845_update_cursor(struct intel_plane *plane,
>  		I915_WRITE_FW(CURPOS(PIPE_A), pos);
>  	}
>  
> -	POSTING_READ_FW(CURCNTR(PIPE_A));
> -
>  	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>  }
>  
> @@ -10080,8 +10076,6 @@ static void i9xx_update_cursor(struct intel_plane *plane,
>  		I915_WRITE_FW(CURBASE(pipe), base);
>  	}
>  
> -	POSTING_READ_FW(CURBASE(pipe));
> -
>  	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>  }
>  
> diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
> index 20b5b9ff782f..bd7d988d7512 100644
> --- a/drivers/gpu/drm/i915/intel_sprite.c
> +++ b/drivers/gpu/drm/i915/intel_sprite.c
> @@ -463,7 +463,6 @@ skl_program_plane(struct intel_plane *plane,
>  	I915_WRITE_FW(PLANE_CTL(pipe, plane_id), plane_ctl);
>  	I915_WRITE_FW(PLANE_SURF(pipe, plane_id),
>  		      intel_plane_ggtt_offset(plane_state) + surf_addr);
> -	POSTING_READ_FW(PLANE_SURF(pipe, plane_id));
>  
>  	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>  }
> @@ -504,9 +503,7 @@ skl_disable_plane(struct intel_plane *plane, struct intel_crtc *crtc)
>  	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
>  
>  	I915_WRITE_FW(PLANE_CTL(pipe, plane_id), 0);
> -
>  	I915_WRITE_FW(PLANE_SURF(pipe, plane_id), 0);
> -	POSTING_READ_FW(PLANE_SURF(pipe, plane_id));
>  
>  	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>  }
> @@ -752,7 +749,6 @@ vlv_update_plane(struct intel_plane *plane,
>  	I915_WRITE_FW(SPCNTR(pipe, plane_id), sprctl);
>  	I915_WRITE_FW(SPSURF(pipe, plane_id),
>  		      intel_plane_ggtt_offset(plane_state) + sprsurf_offset);
> -	POSTING_READ_FW(SPSURF(pipe, plane_id));
>  
>  	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>  }
> @@ -768,9 +764,7 @@ vlv_disable_plane(struct intel_plane *plane, struct intel_crtc *crtc)
>  	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
>  
>  	I915_WRITE_FW(SPCNTR(pipe, plane_id), 0);
> -
>  	I915_WRITE_FW(SPSURF(pipe, plane_id), 0);
> -	POSTING_READ_FW(SPSURF(pipe, plane_id));
>  
>  	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>  }
> @@ -918,7 +912,6 @@ ivb_update_plane(struct intel_plane *plane,
>  	I915_WRITE_FW(SPRCTL(pipe), sprctl);
>  	I915_WRITE_FW(SPRSURF(pipe),
>  		      intel_plane_ggtt_offset(plane_state) + sprsurf_offset);
> -	POSTING_READ_FW(SPRSURF(pipe));
>  
>  	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>  }
> @@ -936,9 +929,7 @@ ivb_disable_plane(struct intel_plane *plane, struct intel_crtc *crtc)
>  	/* Can't leave the scaler enabled... */
>  	if (IS_IVYBRIDGE(dev_priv))
>  		I915_WRITE_FW(SPRSCALE(pipe), 0);
> -
>  	I915_WRITE_FW(SPRSURF(pipe), 0);
> -	POSTING_READ_FW(SPRSURF(pipe));
>  
>  	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>  }
> @@ -1085,7 +1076,6 @@ g4x_update_plane(struct intel_plane *plane,
>  	I915_WRITE_FW(DVSCNTR(pipe), dvscntr);
>  	I915_WRITE_FW(DVSSURF(pipe),
>  		      intel_plane_ggtt_offset(plane_state) + dvssurf_offset);
> -	POSTING_READ_FW(DVSSURF(pipe));
>  
>  	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>  }
> @@ -1102,9 +1092,7 @@ g4x_disable_plane(struct intel_plane *plane, struct intel_crtc *crtc)
>  	I915_WRITE_FW(DVSCNTR(pipe), 0);
>  	/* Disable the scaler */
>  	I915_WRITE_FW(DVSSCALE(pipe), 0);
> -
>  	I915_WRITE_FW(DVSSURF(pipe), 0);
> -	POSTING_READ_FW(DVSSURF(pipe));
>  
>  	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>  }
> -- 
> 2.18.1
> 
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