drm/msm/mdp4: only use lut_clk on mdp4.2+

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c

@@ -206,7 +206,8 @@ int mdp4_disable(struct mdp4_kms *mdp4_kms)
 	clk_disable_unprepare(mdp4_kms->clk);
 	if (mdp4_kms->pclk)
 		clk_disable_unprepare(mdp4_kms->pclk);
-	clk_disable_unprepare(mdp4_kms->lut_clk);
+	if (mdp4_kms->lut_clk)
+		clk_disable_unprepare(mdp4_kms->lut_clk);
 	if (mdp4_kms->axi_clk)
 		clk_disable_unprepare(mdp4_kms->axi_clk);
 
@@ -220,7 +221,8 @@ int mdp4_enable(struct mdp4_kms *mdp4_kms)
 	clk_prepare_enable(mdp4_kms->clk);
 	if (mdp4_kms->pclk)
 		clk_prepare_enable(mdp4_kms->pclk);
-	clk_prepare_enable(mdp4_kms->lut_clk);
+	if (mdp4_kms->lut_clk)
+		clk_prepare_enable(mdp4_kms->lut_clk);
 	if (mdp4_kms->axi_clk)
 		clk_prepare_enable(mdp4_kms->axi_clk);
 
@@ -472,12 +474,13 @@ struct msm_kms *mdp4_kms_init(struct drm_device *dev)
 	if (IS_ERR(mdp4_kms->pclk))
 		mdp4_kms->pclk = NULL;
 
-	// XXX if (rev >= MDP_REV_42) { ???
-	mdp4_kms->lut_clk = devm_clk_get(&pdev->dev, "lut_clk");
-	if (IS_ERR(mdp4_kms->lut_clk)) {
-		DRM_DEV_ERROR(dev->dev, "failed to get lut_clk\n");
-		ret = PTR_ERR(mdp4_kms->lut_clk);
-		goto fail;
+	if (mdp4_kms->rev >= 2) {
+		mdp4_kms->lut_clk = devm_clk_get(&pdev->dev, "lut_clk");
+		if (IS_ERR(mdp4_kms->lut_clk)) {
+			DRM_DEV_ERROR(dev->dev, "failed to get lut_clk\n");
+			ret = PTR_ERR(mdp4_kms->lut_clk);
+			goto fail;
+		}
 	}
 
 	mdp4_kms->axi_clk = devm_clk_get(&pdev->dev, "bus_clk");
@@ -488,7 +491,8 @@ struct msm_kms *mdp4_kms_init(struct drm_device *dev)
 	}
 
 	clk_set_rate(mdp4_kms->clk, config->max_clk);
-	clk_set_rate(mdp4_kms->lut_clk, config->max_clk);
+	if (mdp4_kms->lut_clk)
+		clk_set_rate(mdp4_kms->lut_clk, config->max_clk);
 
 	pm_runtime_enable(dev->dev);
 	mdp4_kms->rpm_enabled = true;