[Intel-gfx] [PATCH 1/2] drm/i915: Add display WA #1175 for planes ending close to right screen edge

[Imre Deak]

As described in the WA on GLK and CNL planes on the right edge of the
screen that have less than 4 pixels visible from the beginning of the
plane to the edge of the screen can cause FIFO underflow and display
corruption.

On GLK/CNL I could trigger the problem only if the plane was at the same
time also aligned to the top edge of the screen (after clipping) and
there were exactly 2 pixels visible from the start of the plane to the
right edge of the screen (so couldn't trigger it with 1 or 3 pixels
visible). Nevertheless, to be sure, I also applied the WA for these cases.

I also couldn't see any problem with the cursor plane and later Art
confirmed that it's not affected, so the WA is applied only for the
other plane types.

Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 28 ++++++++++++++++++++++++----
 drivers/gpu/drm/i915/intel_drv.h     |  3 ++-
 drivers/gpu/drm/i915/intel_sprite.c  |  2 +-
 3 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 221e3a183d36..3d931b652795 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2917,14 +2917,19 @@ static bool skl_check_main_ccs_coordinates(struct intel_plane_state *plane_state
 	return true;
 }
 
-static int skl_check_main_surface(struct intel_plane_state *plane_state)
+static int skl_check_main_surface(const struct intel_crtc_state *crtc_state,
+				  struct intel_plane_state *plane_state)
 {
+	struct drm_i915_private *dev_priv =
+		to_i915(plane_state->base.plane->dev);
 	const struct drm_framebuffer *fb = plane_state->base.fb;
 	unsigned int rotation = plane_state->base.rotation;
 	int x = plane_state->base.src.x1 >> 16;
 	int y = plane_state->base.src.y1 >> 16;
 	int w = drm_rect_width(&plane_state->base.src) >> 16;
 	int h = drm_rect_height(&plane_state->base.src) >> 16;
+	int dst_x = plane_state->base.dst.x1;
+	int pipe_src_w = crtc_state->pipe_src_w;
 	int max_width = skl_max_plane_width(fb, 0, rotation);
 	int max_height = 4096;
 	u32 alignment, offset, aux_offset = plane_state->aux.offset;
@@ -2935,6 +2940,20 @@ static int skl_check_main_surface(struct intel_plane_state *plane_state)
 		return -EINVAL;
 	}
 
+	/*
+	 * Display WA #1175: cnl,glk
+	 * Planes other than the cursor may cause FIFO underflow and display
+	 * corruption if starting less than 4 pixels from the right edge of
+	 * the screen.
+	 */
+	if ((IS_GEMINILAKE(dev_priv) || IS_CANNONLAKE(dev_priv)) &&
+	    dst_x > pipe_src_w - 4) {
+		DRM_DEBUG_KMS("requested plane X start position %d invalid (valid range %d-%d)\n",
+			      dst_x,
+			      0, pipe_src_w - 4);
+		return -EINVAL;
+	}
+
 	intel_add_fb_offsets(&x, &y, plane_state, 0);
 	offset = intel_compute_tile_offset(&x, &y, plane_state, 0);
 	alignment = intel_surf_alignment(fb, 0);
@@ -3067,7 +3086,8 @@ static int skl_check_ccs_aux_surface(struct intel_plane_state *plane_state)
 	return 0;
 }
 
-int skl_check_plane_surface(struct intel_plane_state *plane_state)
+int skl_check_plane_surface(const struct intel_crtc_state *crtc_state,
+			    struct intel_plane_state *plane_state)
 {
 	const struct drm_framebuffer *fb = plane_state->base.fb;
 	unsigned int rotation = plane_state->base.rotation;
@@ -3107,7 +3127,7 @@ int skl_check_plane_surface(struct intel_plane_state *plane_state)
 		plane_state->aux.y = 0;
 	}
 
-	ret = skl_check_main_surface(plane_state);
+	ret = skl_check_main_surface(crtc_state, plane_state);
 	if (ret)
 		return ret;
 
@@ -12766,7 +12786,7 @@ intel_check_primary_plane(struct intel_plane *plane,
 		return 0;
 
 	if (INTEL_GEN(dev_priv) >= 9) {
-		ret = skl_check_plane_surface(state);
+		ret = skl_check_plane_surface(crtc_state, state);
 		if (ret)
 			return ret;
 
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 731dc36d7129..5e23da04837e 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1588,7 +1588,8 @@ u32 skl_plane_ctl(const struct intel_crtc_state *crtc_state,
 		  const struct intel_plane_state *plane_state);
 u32 skl_plane_stride(const struct drm_framebuffer *fb, int plane,
 		     unsigned int rotation);
-int skl_check_plane_surface(struct intel_plane_state *plane_state);
+int skl_check_plane_surface(const struct intel_crtc_state *crtc_state,
+			    struct intel_plane_state *plane_state);
 int i9xx_check_plane_surface(struct intel_plane_state *plane_state);
 
 /* intel_csr.c */
diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
index dd485f59eb1d..b8b617ba0c0c 100644
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -1027,7 +1027,7 @@ intel_check_sprite_plane(struct intel_plane *plane,
 	dst->y2 = crtc_y + crtc_h;
 
 	if (INTEL_GEN(dev_priv) >= 9) {
-		ret = skl_check_plane_surface(state);
+		ret = skl_check_plane_surface(crtc_state, state);
 		if (ret)
 			return ret;
 
-- 
2.13.2