[Intel-gfx] [RFC][PATCH 14/14] WIP/drm/i915: Nuke posting reads from plane updates

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

We'll maybe want just one posting read at the end? This does seem to
potentially shave a few usec off from the update.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 8 --------
 drivers/gpu/drm/i915/intel_sprite.c  | 8 --------
 2 files changed, 16 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index c35818b42762..d9ec654db5a3 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3125,7 +3125,6 @@ static void i9xx_update_primary_plane(struct drm_plane *primary,
 			      intel_plane_ggtt_offset(plane_state) +
 			      intel_crtc->dspaddr_offset);
 	}
-	POSTING_READ_FW(reg);
 }
 
 static void i9xx_disable_primary_plane(struct drm_plane *primary,
@@ -3141,7 +3140,6 @@ static void i9xx_disable_primary_plane(struct drm_plane *primary,
 		I915_WRITE_FW(DSPSURF(plane), 0);
 	else
 		I915_WRITE_FW(DSPADDR(plane), 0);
-	POSTING_READ_FW(DSPCNTR(plane));
 }
 
 static u32
@@ -3379,7 +3377,6 @@ static void skylake_update_primary_plane(struct drm_plane *plane,
 	I915_WRITE_FW(PLANE_SURF(pipe, plane_id),
 		      intel_plane_ggtt_offset(plane_state) + surf_addr);
 
-	POSTING_READ_FW(PLANE_SURF(pipe, plane_id));
 }
 
 static void skylake_disable_primary_plane(struct drm_plane *primary,
@@ -3392,7 +3389,6 @@ static void skylake_disable_primary_plane(struct drm_plane *primary,
 
 	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));
 }
 
 /* Assume fb object is pinned & idle & fenced and just update base pointers */
@@ -9171,7 +9167,6 @@ static void i845_update_cursor(struct drm_crtc *crtc, u32 base,
 		 * whilst the cursor is disabled.
 		 */
 		I915_WRITE_FW(CURCNTR(PIPE_A), 0);
-		POSTING_READ_FW(CURCNTR(PIPE_A));
 		intel_crtc->cursor_cntl = 0;
 	}
 
@@ -9187,7 +9182,6 @@ static void i845_update_cursor(struct drm_crtc *crtc, u32 base,
 
 	if (intel_crtc->cursor_cntl != cntl) {
 		I915_WRITE_FW(CURCNTR(PIPE_A), cntl);
-		POSTING_READ_FW(CURCNTR(PIPE_A));
 		intel_crtc->cursor_cntl = cntl;
 	}
 }
@@ -9243,13 +9237,11 @@ static void i9xx_update_cursor(struct drm_crtc *crtc, u32 base,
 
 	if (intel_crtc->cursor_cntl != cntl) {
 		I915_WRITE_FW(CURCNTR(pipe), cntl);
-		POSTING_READ_FW(CURCNTR(pipe));
 		intel_crtc->cursor_cntl = cntl;
 	}
 
 	/* and commit changes on next vblank */
 	I915_WRITE_FW(CURBASE(pipe), base);
-	POSTING_READ_FW(CURBASE(pipe));
 
 	intel_crtc->cursor_base = base;
 }
diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
index 06c89deca36b..5cf88f95c23e 100644
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -288,7 +288,6 @@ skl_update_plane(struct drm_plane *drm_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));
 }
 
 static void
@@ -303,7 +302,6 @@ skl_disable_plane(struct drm_plane *dplane, struct drm_crtc *crtc)
 	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));
 }
 
 static void
@@ -459,7 +457,6 @@ vlv_update_plane(struct drm_plane *dplane,
 	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));
 }
 
 static void
@@ -474,7 +471,6 @@ vlv_disable_plane(struct drm_plane *dplane, struct drm_crtc *crtc)
 	I915_WRITE_FW(SPCNTR(pipe, plane_id), 0);
 
 	I915_WRITE_FW(SPSURF(pipe, plane_id), 0);
-	POSTING_READ_FW(SPSURF(pipe, plane_id));
 }
 
 static u32 ivb_sprite_ctl(const struct intel_crtc_state *crtc_state,
@@ -591,7 +587,6 @@ ivb_update_plane(struct drm_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));
 }
 
 static void
@@ -608,7 +603,6 @@ ivb_disable_plane(struct drm_plane *plane, struct drm_crtc *crtc)
 		I915_WRITE_FW(SPRSCALE(pipe), 0);
 
 	I915_WRITE_FW(SPRSURF(pipe), 0);
-	POSTING_READ_FW(SPRSURF(pipe));
 }
 
 static u32 ilk_sprite_ctl(const struct intel_crtc_state *crtc_state,
@@ -717,7 +711,6 @@ ilk_update_plane(struct drm_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));
 }
 
 static void
@@ -733,7 +726,6 @@ ilk_disable_plane(struct drm_plane *plane, struct drm_crtc *crtc)
 	I915_WRITE_FW(DVSSCALE(pipe), 0);
 
 	I915_WRITE_FW(DVSSURF(pipe), 0);
-	POSTING_READ_FW(DVSSURF(pipe));
 }
 
 static int
-- 
2.10.2