drm/exynos: fimd: fix dma burst size setting for small plane size

This patch fixes trashed display of buffers cropped to very small width.
Even if DMA is unstable and causes tearing when changing the burst size,
it is still better than displaying a garbage.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_fimd.c

@@ -487,7 +487,7 @@ static void fimd_commit(struct exynos_drm_crtc *crtc)
 
 
 static void fimd_win_set_pixfmt(struct fimd_context *ctx, unsigned int win,
-				struct drm_framebuffer *fb)
+				uint32_t pixel_format, int width)
 {
 	unsigned long val;
 
@@ -498,11 +498,11 @@ static void fimd_win_set_pixfmt(struct fimd_context *ctx, unsigned int win,
 	 * So the request format is ARGB8888 then change it to XRGB8888.
 	 */
 	if (ctx->driver_data->has_limited_fmt && !win) {
-		if (fb->pixel_format == DRM_FORMAT_ARGB8888)
-			fb->pixel_format = DRM_FORMAT_XRGB8888;
+		if (pixel_format == DRM_FORMAT_ARGB8888)
+			pixel_format = DRM_FORMAT_XRGB8888;
 	}
 
-	switch (fb->pixel_format) {
+	switch (pixel_format) {
 	case DRM_FORMAT_C8:
 		val |= WINCON0_BPPMODE_8BPP_PALETTE;
 		val |= WINCONx_BURSTLEN_8WORD;
@@ -538,17 +538,15 @@ static void fimd_win_set_pixfmt(struct fimd_context *ctx, unsigned int win,
 		break;
 	}
 
-	DRM_DEBUG_KMS("bpp = %d\n", fb->bits_per_pixel);
-
 	/*
-	 * In case of exynos, setting dma-burst to 16Word causes permanent
-	 * tearing for very small buffers, e.g. cursor buffer. Burst Mode
-	 * switching which is based on plane size is not recommended as
-	 * plane size varies alot towards the end of the screen and rapid
-	 * movement causes unstable DMA which results into iommu crash/tear.
+	 * Setting dma-burst to 16Word causes permanent tearing for very small
+	 * buffers, e.g. cursor buffer. Burst Mode switching which based on
+	 * plane size is not recommended as plane size varies alot towards the
+	 * end of the screen and rapid movement causes unstable DMA, but it is
+	 * still better to change dma-burst than displaying garbage.
 	 */
 
-	if (fb->width < MIN_FB_WIDTH_FOR_16WORD_BURST) {
+	if (width < MIN_FB_WIDTH_FOR_16WORD_BURST) {
 		val &= ~WINCONx_BURSTLEN_MASK;
 		val |= WINCONx_BURSTLEN_4WORD;
 	}
@@ -723,7 +721,7 @@ static void fimd_update_plane(struct exynos_drm_crtc *crtc,
 		DRM_DEBUG_KMS("osd size = 0x%x\n", (unsigned int)val);
 	}
 
-	fimd_win_set_pixfmt(ctx, win, fb);
+	fimd_win_set_pixfmt(ctx, win, fb->pixel_format, state->src.w);
 
 	/* hardware window 0 doesn't support color key. */
 	if (win != 0)