drm/i915: Handle untiled planes when computing their offsets

We trim the fb to fit the CRTC by computing the offset of that CRTC to
its nearest tile_row origin. This allows us to use framebuffers that are
larger than the CRTC limits without additional work.

However, we failed to compute the offset for a linear framebuffer
correctly as we treated its x-advance in whole tiles (instead of the
linear increment expected), leaving the CRTC misaligned with its
contents.

Fixes regression from commit c2c7513
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Thu Jul 5 12:17:30 2012 +0200

    drm/i915: adjust framebuffer base address on gen4+

v2: Adjust relative x-coordinate after linear alignment (vsyrjala)
v3: Repaint with pokadots (vsyrjala)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61152
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -2001,18 +2001,29 @@ void intel_unpin_fb_obj(struct drm_i915_gem_object *obj)
 
 /* Computes the linear offset to the base tile and adjusts x, y. bytes per pixel
  * is assumed to be a power-of-two. */
-unsigned long intel_gen4_compute_offset_xtiled(int *x, int *y,
-					       unsigned int bpp,
-					       unsigned int pitch)
+unsigned long intel_gen4_compute_page_offset(int *x, int *y,
+					     unsigned int tiling_mode,
+					     unsigned int cpp,
+					     unsigned int pitch)
 {
-	int tile_rows, tiles;
+	if (tiling_mode != I915_TILING_NONE) {
+		unsigned int tile_rows, tiles;
 
-	tile_rows = *y / 8;
-	*y %= 8;
-	tiles = *x / (512/bpp);
-	*x %= 512/bpp;
+		tile_rows = *y / 8;
+		*y %= 8;
 
-	return tile_rows * pitch * 8 + tiles * 4096;
+		tiles = *x / (512/cpp);
+		*x %= 512/cpp;
+
+		return tile_rows * pitch * 8 + tiles * 4096;
+	} else {
+		unsigned int offset;
+
+		offset = *y * pitch + *x * cpp;
+		*y = 0;
+		*x = (offset & 4095) / cpp;
+		return offset & -4096;
+	}
 }
 
 static int i9xx_update_plane(struct drm_crtc *crtc, struct drm_framebuffer *fb,
@@ -2089,9 +2100,9 @@ static int i9xx_update_plane(struct drm_crtc *crtc, struct drm_framebuffer *fb,
 
 	if (INTEL_INFO(dev)->gen >= 4) {
 		intel_crtc->dspaddr_offset =
-			intel_gen4_compute_offset_xtiled(&x, &y,
-							 fb->bits_per_pixel / 8,
-							 fb->pitches[0]);
+			intel_gen4_compute_page_offset(&x, &y, obj->tiling_mode,
+						       fb->bits_per_pixel / 8,
+						       fb->pitches[0]);
 		linear_offset -= intel_crtc->dspaddr_offset;
 	} else {
 		intel_crtc->dspaddr_offset = linear_offset;
@@ -2182,9 +2193,9 @@ static int ironlake_update_plane(struct drm_crtc *crtc,
 
 	linear_offset = y * fb->pitches[0] + x * (fb->bits_per_pixel / 8);
 	intel_crtc->dspaddr_offset =
-		intel_gen4_compute_offset_xtiled(&x, &y,
-						 fb->bits_per_pixel / 8,
-						 fb->pitches[0]);
+		intel_gen4_compute_page_offset(&x, &y, obj->tiling_mode,
+					       fb->bits_per_pixel / 8,
+					       fb->pitches[0]);
 	linear_offset -= intel_crtc->dspaddr_offset;
 
 	DRM_DEBUG_KMS("Writing base %08X %08lX %d %d %d\n",

drivers/gpu/drm/i915/intel_drv.h

@@ -649,9 +649,10 @@ extern void intel_update_sprite_watermarks(struct drm_device *dev, int pipe,
 extern void intel_update_linetime_watermarks(struct drm_device *dev, int pipe,
 			 struct drm_display_mode *mode);
 
-extern unsigned long intel_gen4_compute_offset_xtiled(int *x, int *y,
-						      unsigned int bpp,
-						      unsigned int pitch);
+extern unsigned long intel_gen4_compute_page_offset(int *x, int *y,
+						    unsigned int tiling_mode,
+						    unsigned int bpp,
+						    unsigned int pitch);
 
 extern int intel_sprite_set_colorkey(struct drm_device *dev, void *data,
 				     struct drm_file *file_priv);

drivers/gpu/drm/i915/intel_sprite.c

@@ -122,8 +122,8 @@ ivb_update_plane(struct drm_plane *plane, struct drm_framebuffer *fb,
 
 	linear_offset = y * fb->pitches[0] + x * pixel_size;
 	sprsurf_offset =
-		intel_gen4_compute_offset_xtiled(&x, &y,
-						 pixel_size, fb->pitches[0]);
+		intel_gen4_compute_page_offset(&x, &y, obj->tiling_mode,
+					       pixel_size, fb->pitches[0]);
 	linear_offset -= sprsurf_offset;
 
 	/* HSW consolidates SPRTILEOFF and SPRLINOFF into a single SPROFFSET
@@ -295,8 +295,8 @@ ilk_update_plane(struct drm_plane *plane, struct drm_framebuffer *fb,
 
 	linear_offset = y * fb->pitches[0] + x * pixel_size;
 	dvssurf_offset =
-		intel_gen4_compute_offset_xtiled(&x, &y,
-						 pixel_size, fb->pitches[0]);
+		intel_gen4_compute_page_offset(&x, &y, obj->tiling_mode,
+					       pixel_size, fb->pitches[0]);
 	linear_offset -= dvssurf_offset;
 
 	if (obj->tiling_mode != I915_TILING_NONE)