drm: sti: clear all mixer control

Make sure that mixer control register is correctly reset
before use it.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>

3 files changed, 12 insertions, 0 deletions

diff --git a/drivers/gpu/drm/sti/sti_drm_crtc.c b/drivers/gpu/drm/sti/sti_drm_crtc.c
index 36a1ad3c4823..d42c63f756ef 100644
--- a/drivers/gpu/drm/sti/sti_drm_crtc.c
+++ b/drivers/gpu/drm/sti/sti_drm_crtc.c
@@ -38,6 +38,8 @@ static void sti_drm_crtc_prepare(struct drm_crtc *crtc)
                 if (clk_prepare_enable(compo->clk_compo_aux))
                         DRM_INFO("Failed to prepare/enable compo_aux clk\n");
         }
+
+        sti_mixer_clear_all_layers(mixer);
 }
 
 static void sti_drm_crtc_commit(struct drm_crtc *crtc)
diff --git a/drivers/gpu/drm/sti/sti_mixer.c b/drivers/gpu/drm/sti/sti_mixer.c
index 79f369db9fb6..6bcdf3f86d22 100644
--- a/drivers/gpu/drm/sti/sti_mixer.c
+++ b/drivers/gpu/drm/sti/sti_mixer.c
@@ -215,6 +215,15 @@ int sti_mixer_set_layer_status(struct sti_mixer *mixer,
         return 0;
 }
 
+void sti_mixer_clear_all_layers(struct sti_mixer *mixer)
+{
+        u32 val;
+
+        DRM_DEBUG_DRIVER("%s clear all layer\n", sti_mixer_to_str(mixer));
+        val = sti_mixer_reg_read(mixer, GAM_MIXER_CTL) & 0xFFFF0000;
+        sti_mixer_reg_write(mixer, GAM_MIXER_CTL, val);
+}
+
 void sti_mixer_set_matrix(struct sti_mixer *mixer)
 {
         unsigned int i;
diff --git a/drivers/gpu/drm/sti/sti_mixer.h b/drivers/gpu/drm/sti/sti_mixer.h
index 874372102e52..750e1fd5a8ce 100644
--- a/drivers/gpu/drm/sti/sti_mixer.h
+++ b/drivers/gpu/drm/sti/sti_mixer.h
@@ -39,6 +39,7 @@ struct sti_mixer *sti_mixer_create(struct device *dev, int id,
 
 int sti_mixer_set_layer_status(struct sti_mixer *mixer,
                 struct sti_layer *layer, bool status);
+void sti_mixer_clear_all_layers(struct sti_mixer *mixer);
 int sti_mixer_set_layer_depth(struct sti_mixer *mixer, struct sti_layer *layer);
 int sti_mixer_active_video_area(struct sti_mixer *mixer,
                 struct drm_display_mode *mode);