[PATCH] drm/arm/malidp: Preserve LAYER_FORMAT contents when setting format

[PATCH] drm/arm/malidp: Preserve LAYER_FORMAT contents when setting format

[Ayan Kumar Halder]

On some Mali-DP processors, the LAYER_FORMAT register contains fields
other than the format. These bits were unconditionally cleared when
setting the pixel format, whereas they should be preserved at their
reset values.

Reported-by: Brian Starkey <brian.starkey@arm.com>
Reported-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Ayan Kumar halder <ayan.halder@arm.com>
---
 drivers/gpu/drm/arm/malidp_planes.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/arm/malidp_planes.c b/drivers/gpu/drm/arm/malidp_planes.c
index 7a44897..4af3c1f 100644
--- a/drivers/gpu/drm/arm/malidp_planes.c
+++ b/drivers/gpu/drm/arm/malidp_planes.c
@@ -23,6 +23,7 @@
 
 /* Layer specific register offsets */
 #define MALIDP_LAYER_FORMAT		0x000
+#define   LAYER_FORMAT_MASK		0x3f
 #define MALIDP_LAYER_CONTROL		0x004
 #define   LAYER_ENABLE			(1 << 0)
 #define   LAYER_FLOWCFG_MASK		7
@@ -337,7 +338,9 @@ static void malidp_de_plane_update(struct drm_plane *plane,
 	dest_w = plane->state->crtc_w;
 	dest_h = plane->state->crtc_h;
 
-	malidp_hw_write(mp->hwdev, ms->format, mp->layer->base);
+	val = malidp_hw_read(mp->hwdev, mp->layer->base);
+	val = (val & ~LAYER_FORMAT_MASK) | ms->format;
+	malidp_hw_write(mp->hwdev, val, mp->layer->base);
 
 	for (i = 0; i < ms->n_planes; i++) {
 		/* calculate the offset for the layer's plane registers */
-- 
2.7.4

Re: [PATCH] drm/arm/malidp: Preserve LAYER_FORMAT contents when setting format

[Liviu Dudau]

On Tue, Apr 10, 2018 at 07:25:03PM +0100, Ayan Kumar Halder wrote:
> On some Mali-DP processors, the LAYER_FORMAT register contains fields
> other than the format. These bits were unconditionally cleared when
> setting the pixel format, whereas they should be preserved at their
> reset values.
> 
> Reported-by: Brian Starkey <brian.starkey@arm.com>
> Reported-by: Liviu Dudau <liviu.dudau@arm.com>
> Signed-off-by: Ayan Kumar halder <ayan.halder@arm.com>

Acked-by: Liviu Dudau <liviu.dudau@arm.com>

Thanks for catching this in testing!

Best regards,
Liviu

> ---
>  drivers/gpu/drm/arm/malidp_planes.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/arm/malidp_planes.c b/drivers/gpu/drm/arm/malidp_planes.c
> index 7a44897..4af3c1f 100644
> --- a/drivers/gpu/drm/arm/malidp_planes.c
> +++ b/drivers/gpu/drm/arm/malidp_planes.c
> @@ -23,6 +23,7 @@
>  
>  /* Layer specific register offsets */
>  #define MALIDP_LAYER_FORMAT		0x000
> +#define   LAYER_FORMAT_MASK		0x3f
>  #define MALIDP_LAYER_CONTROL		0x004
>  #define   LAYER_ENABLE			(1 << 0)
>  #define   LAYER_FLOWCFG_MASK		7
> @@ -337,7 +338,9 @@ static void malidp_de_plane_update(struct drm_plane *plane,
>  	dest_w = plane->state->crtc_w;
>  	dest_h = plane->state->crtc_h;
>  
> -	malidp_hw_write(mp->hwdev, ms->format, mp->layer->base);
> +	val = malidp_hw_read(mp->hwdev, mp->layer->base);
> +	val = (val & ~LAYER_FORMAT_MASK) | ms->format;
> +	malidp_hw_write(mp->hwdev, val, mp->layer->base);
>  
>  	for (i = 0; i < ms->n_planes; i++) {
>  		/* calculate the offset for the layer's plane registers */
> -- 
> 2.7.4
> 

-- 
====================
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| but they're not |
| giving me the   |
 \ source code!  /
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