drm/rockchip: fix clk enable disable mismatch in vop_crtc_mode_set

The function disables the dclk at the beginning, so don't simply return
when an error happens, but instead enable the clock again, so that
enable and disable calls are balanced.

ret_clk is introduced to hold the clk_enable result and not mangle the
original error code.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>

drivers/gpu/drm/rockchip/rockchip_drm_vop.c

@@ -893,7 +893,7 @@ static int vop_crtc_mode_set(struct drm_crtc *crtc,
 	u16 vsync_len = adjusted_mode->vsync_end - adjusted_mode->vsync_start;
 	u16 vact_st = adjusted_mode->vtotal - adjusted_mode->vsync_start;
 	u16 vact_end = vact_st + vdisplay;
-	int ret;
+	int ret, ret_clk;
 	uint32_t val;
 
 	/*
@@ -915,7 +915,8 @@ static int vop_crtc_mode_set(struct drm_crtc *crtc,
 	default:
 		DRM_ERROR("unsupport connector_type[%d]\n",
 			  vop->connector_type);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto out;
 	};
 	VOP_CTRL_SET(vop, out_mode, vop->connector_out_mode);
 
@@ -938,7 +939,7 @@ static int vop_crtc_mode_set(struct drm_crtc *crtc,
 
 	ret = vop_crtc_mode_set_base(crtc, x, y, fb);
 	if (ret)
-		return ret;
+		goto out;
 
 	/*
 	 * reset dclk, take all mode config affect, so the clk would run in
@@ -949,13 +950,14 @@ static int vop_crtc_mode_set(struct drm_crtc *crtc,
 	reset_control_deassert(vop->dclk_rst);
 
 	clk_set_rate(vop->dclk, adjusted_mode->clock * 1000);
-	ret = clk_enable(vop->dclk);
-	if (ret < 0) {
-		dev_err(vop->dev, "failed to enable dclk - %d\n", ret);
-		return ret;
+out:
+	ret_clk = clk_enable(vop->dclk);
+	if (ret_clk < 0) {
+		dev_err(vop->dev, "failed to enable dclk - %d\n", ret_clk);
+		return ret_clk;
 	}
 
-	return 0;
+	return ret;
 }
 
 static void vop_crtc_commit(struct drm_crtc *crtc)