drm/arm/malidp: Preserve LAYER_FORMAT contents when setting format

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

diff --git a/drivers/gpu/drm/arm/malidp_planes.c b/drivers/gpu/drm/arm/malidp_planes.c
index 7a44897c50fea784bf516db7f17866ee31f413fa..4af3c1fabb2303193f84ffc823f81c89e5587cb4 100644 (file)
--- 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 */