diff mbox

[18/25] drm/exynos: fimd: fix dma burst size setting for small plane size

Message ID 1447161821-1877-19-git-send-email-m.szyprowski@samsung.com (mailing list archive)
State New, archived
Headers show

Commit Message

Marek Szyprowski Nov. 10, 2015, 1:23 p.m. UTC
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>
---
 drivers/gpu/drm/exynos/exynos_drm_fimd.c | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

Comments

Tobias Jakobi Nov. 12, 2015, 3:17 p.m. UTC | #1
This one looks a bit strange. It only changes the argument list of
fimd_win_set_pixfmt() but the commit message that it actually fixes
something.

The corresponding upstream commit:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=66367461e573321f0fbb0be0391165b5a54d5fe4

With best wishes,
Tobias


Marek Szyprowski wrote:
> 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>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_fimd.c | 24 +++++++++++-------------
>  1 file changed, 11 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
> index 44226b2b46c7..6c04ff6432d4 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c
> +++ b/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)
> 

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Daniel Stone Nov. 12, 2015, 3:23 p.m. UTC | #2
Hey Tobias,

On 12 November 2015 at 15:17, Tobias Jakobi
<tjakobi@math.uni-bielefeld.de> wrote:
> This one looks a bit strange. It only changes the argument list of
> fimd_win_set_pixfmt() but the commit message that it actually fixes
> something.
>
> The corresponding upstream commit:
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=66367461e573321f0fbb0be0391165b5a54d5fe4

It's subtle:

>> -     fimd_win_set_pixfmt(ctx, win, fb);
>> +     fimd_win_set_pixfmt(ctx, win, fb->pixel_format, state->src.w);

i.e. rather than checking the total width of the allocated fb, we
check the width we are _actually_ scanning out from the fb. So I think
the patch is correct.

Cheers,
Daniel
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diff mbox

Patch

diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
index 44226b2b46c7..6c04ff6432d4 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c
+++ b/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)