drm/sti: enable gdp pixel clock in atomic_update

Set gdp pix clock rate and parent in atomic_check function and enable
it in the atomic_update only the first time.
Signed-off-by: Vincent Abriou <vincent.abriou@st.com>

drivers/gpu/drm/sti/sti_gdp.c

@@ -610,7 +610,6 @@ static int sti_gdp_atomic_check(struct drm_plane *drm_plane,
 	struct sti_plane *plane = to_sti_plane(drm_plane);
 	struct sti_gdp *gdp = to_sti_gdp(plane);
 	struct drm_crtc *crtc = state->crtc;
-	struct sti_compositor *compo = dev_get_drvdata(gdp->dev);
 	struct drm_framebuffer *fb =  state->fb;
 	struct drm_crtc_state *crtc_state;
 	struct sti_mixer *mixer;
@@ -648,16 +647,7 @@ static int sti_gdp_atomic_check(struct drm_plane *drm_plane,
 		return -EINVAL;
 	}
 
-	if (!gdp->vtg) {
-		/* Register gdp callback */
-		gdp->vtg = compo->vtg[mixer->id];
-		if (sti_vtg_register_client(gdp->vtg,
-					    &gdp->vtg_field_nb, crtc)) {
-			DRM_ERROR("Cannot register VTG notifier\n");
-			return -EINVAL;
-		}
-
-		/* Set and enable gdp clock */
+	/* Set gdp clock */
 	if (gdp->clk_pix) {
 		struct clk *clkp;
 		int rate = mode->clock * 1000;
@@ -681,12 +671,6 @@ static int sti_gdp_atomic_check(struct drm_plane *drm_plane,
 				  rate);
 			return -EINVAL;
 		}
-
-			if (clk_prepare_enable(gdp->clk_pix)) {
-				DRM_ERROR("Failed to prepare/enable gdp\n");
-				return -EINVAL;
-			}
-		}
 	}
 
 	DRM_DEBUG_KMS("CRTC:%d (%s) drm plane:%d (%s)\n",
@@ -724,6 +708,16 @@ static void sti_gdp_atomic_update(struct drm_plane *drm_plane,
 	if (!crtc || !fb)
 		return;
 
+	if (!gdp->vtg) {
+		struct sti_compositor *compo = dev_get_drvdata(gdp->dev);
+		struct sti_mixer *mixer = to_sti_mixer(crtc);
+
+		/* Register gdp callback */
+		gdp->vtg = compo->vtg[mixer->id];
+		sti_vtg_register_client(gdp->vtg, &gdp->vtg_field_nb, crtc);
+		clk_prepare_enable(gdp->clk_pix);
+	}
+
 	mode = &crtc->mode;
 	dst_x = state->crtc_x;
 	dst_y = state->crtc_y;