[PATCH 3/9] drm: sti: clear all mixer control

[Benjamin Gaignard]

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

Signed-off-by: Benjamin Gaignard <benjamin.gaignard at linaro.org>
---
 drivers/gpu/drm/sti/sti_drm_crtc.c | 2 ++
 drivers/gpu/drm/sti/sti_mixer.c    | 9 +++++++++
 drivers/gpu/drm/sti/sti_mixer.h    | 1 +
 3 files changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/sti/sti_drm_crtc.c b/drivers/gpu/drm/sti/sti_drm_crtc.c
index d2ae0c0..e1e5550 100644
--- a/drivers/gpu/drm/sti/sti_drm_crtc.c
+++ b/drivers/gpu/drm/sti/sti_drm_crtc.c
@@ -37,6 +37,8 @@ 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 79f369d..6bcdf3f 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 8743721..750e1fd 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);
-- 
1.9.1