drm: sti: fix clocking issues in crtc

fix and simplify clock management in crtc to avoid unbalanced
call to clk_prepare_enable and clk_disable_unprepare functions
remove unused functions

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

drivers/gpu/drm/sti/sti_crtc.c

@@ -23,22 +23,11 @@
 static void sti_crtc_enable(struct drm_crtc *crtc)
 {
 	struct sti_mixer *mixer = to_sti_mixer(crtc);
-	struct device *dev = mixer->dev;
-	struct sti_compositor *compo = dev_get_drvdata(dev);
 
 	DRM_DEBUG_DRIVER("\n");
 
 	mixer->status = STI_MIXER_READY;
 
-	/* Prepare and enable the compo IP clock */
-	if (mixer->id == STI_MIXER_MAIN) {
-		if (clk_prepare_enable(compo->clk_compo_main))
-			DRM_INFO("Failed to prepare/enable compo_main clk\n");
-	} else {
-		if (clk_prepare_enable(compo->clk_compo_aux))
-			DRM_INFO("Failed to prepare/enable compo_aux clk\n");
-	}
-
 	drm_crtc_vblank_on(crtc);
 }
 
@@ -57,9 +46,8 @@ sti_crtc_mode_set(struct drm_crtc *crtc, struct drm_display_mode *mode)
 	struct sti_mixer *mixer = to_sti_mixer(crtc);
 	struct device *dev = mixer->dev;
 	struct sti_compositor *compo = dev_get_drvdata(dev);
-	struct clk *clk;
+	struct clk *compo_clk, *pix_clk;
 	int rate = mode->clock * 1000;
-	int res;
 
 	DRM_DEBUG_KMS("CRTC:%d (%s) mode:%d (%s)\n",
 		      crtc->base.id, sti_mixer_to_str(mixer),
@@ -74,32 +62,46 @@ sti_crtc_mode_set(struct drm_crtc *crtc, struct drm_display_mode *mode)
 		      mode->vsync_start, mode->vsync_end,
 		      mode->vtotal, mode->type, mode->flags);
 
-	/* Set rate and prepare/enable pixel clock */
-	if (mixer->id == STI_MIXER_MAIN)
-		clk = compo->clk_pix_main;
-	else
-		clk = compo->clk_pix_aux;
+	if (mixer->id == STI_MIXER_MAIN) {
+		compo_clk = compo->clk_compo_main;
+		pix_clk = compo->clk_pix_main;
+	} else {
+		compo_clk = compo->clk_compo_aux;
+		pix_clk = compo->clk_pix_aux;
+	}
+
+	/* Prepare and enable the compo IP clock */
+	if (clk_prepare_enable(compo_clk)) {
+		DRM_INFO("Failed to prepare/enable compositor clk\n");
+		goto compo_error;
+	}
 
-	res = clk_set_rate(clk, rate);
-	if (res < 0) {
+	/* Set rate and prepare/enable pixel clock */
+	if (clk_set_rate(pix_clk, rate) < 0) {
 		DRM_ERROR("Cannot set rate (%dHz) for pix clk\n", rate);
-		return -EINVAL;
+		goto pix_error;
 	}
-	if (clk_prepare_enable(clk)) {
+	if (clk_prepare_enable(pix_clk)) {
 		DRM_ERROR("Failed to prepare/enable pix clk\n");
-		return -EINVAL;
+		goto pix_error;
 	}
 
 	sti_vtg_set_config(mixer->id == STI_MIXER_MAIN ?
 			compo->vtg_main : compo->vtg_aux, &crtc->mode);
 
-	res = sti_mixer_active_video_area(mixer, &crtc->mode);
-	if (res) {
+	if (sti_mixer_active_video_area(mixer, &crtc->mode)) {
 		DRM_ERROR("Can't set active video area\n");
-		return -EINVAL;
+		goto mixer_error;
 	}
 
-	return res;
+	return 0;
+
+mixer_error:
+	clk_disable_unprepare(pix_clk);
+pix_error:
+	clk_disable_unprepare(compo_clk);
+compo_error:
+	return -EINVAL;
 }
 
 static void sti_crtc_disable(struct drm_crtc *crtc)
@@ -130,7 +132,6 @@ static void sti_crtc_disable(struct drm_crtc *crtc)
 static void
 sti_crtc_mode_set_nofb(struct drm_crtc *crtc)
 {
-	sti_crtc_enable(crtc);
 	sti_crtc_mode_set(crtc, &crtc->state->adjusted_mode);
 }
 
@@ -221,9 +222,7 @@ static void sti_crtc_atomic_flush(struct drm_crtc *crtc,
 static const struct drm_crtc_helper_funcs sti_crtc_helper_funcs = {
 	.enable = sti_crtc_enable,
 	.disable = sti_crtc_disabling,
-	.mode_set = drm_helper_crtc_mode_set,
 	.mode_set_nofb = sti_crtc_mode_set_nofb,
-	.mode_set_base = drm_helper_crtc_mode_set_base,
 	.atomic_begin = sti_crtc_atomic_begin,
 	.atomic_flush = sti_crtc_atomic_flush,
 };