drm/msm/mdp5: Avoid printing error messages for optional clocks

The current behavior is to try to get optional clocks and print a
dev_err message in case of failure. This looks rather confusing
and may increase with the amount of optional clocks.

We may need a cleaner way to handle per-device clocks but in the
meantime, let's reduce the amount of dev_err messages during the
probe.

Signed-off-by: Stephane Viau <sviau@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

2 files changed, 18 insertions, 12 deletions

diff --git a/Documentation/devicetree/bindings/drm/msm/mdp.txt b/Documentation/devicetree/bindings/drm/msm/mdp.txt
index 1a0598e5279d..0833edaba4c3 100644
--- a/Documentation/devicetree/bindings/drm/msm/mdp.txt
+++ b/Documentation/devicetree/bindings/drm/msm/mdp.txt
@@ -11,13 +11,14 @@ Required properties:
 - clock-names: the following clocks are required:
   * "core_clk"
   * "iface_clk"
-  * "lut_clk"
   * "src_clk"
   * "hdmi_clk"
   * "mpd_clk"
 
 Optional properties:
 - gpus: phandle for gpu device
+- clock-names: the following clocks are optional:
+  * "lut_clk"
 
 Example:
 
diff --git a/drivers/gpu/drm/msm/mdp/mdp5/mdp5_kms.c b/drivers/gpu/drm/msm/mdp/mdp5/mdp5_kms.c
index 7dbdced1fa3c..34c4ad54c269 100644
--- a/drivers/gpu/drm/msm/mdp/mdp5/mdp5_kms.c
+++ b/drivers/gpu/drm/msm/mdp/mdp5/mdp5_kms.c
@@ -452,15 +452,19 @@ static void read_hw_revision(struct mdp5_kms *mdp5_kms,
 }
 
 static int get_clk(struct platform_device *pdev, struct clk **clkp,
-                const char *name)
+                const char *name, bool mandatory)
 {
         struct device *dev = &pdev->dev;
         struct clk *clk = devm_clk_get(dev, name);
-        if (IS_ERR(clk)) {
+        if (IS_ERR(clk) && mandatory) {
                 dev_err(dev, "failed to get %s (%ld)\n", name, PTR_ERR(clk));
                 return PTR_ERR(clk);
         }
-        *clkp = clk;
+        if (IS_ERR(clk))
+                DBG("skipping %s", name);
+        else
+                *clkp = clk;
+
         return 0;
 }
 
@@ -514,25 +518,26 @@ struct msm_kms *mdp5_kms_init(struct drm_device *dev)
                 goto fail;
         }
 
-        ret = get_clk(pdev, &mdp5_kms->axi_clk, "bus_clk");
+        /* mandatory clocks: */
+        ret = get_clk(pdev, &mdp5_kms->axi_clk, "bus_clk", true);
         if (ret)
                 goto fail;
-        ret = get_clk(pdev, &mdp5_kms->ahb_clk, "iface_clk");
+        ret = get_clk(pdev, &mdp5_kms->ahb_clk, "iface_clk", true);
         if (ret)
                 goto fail;
-        ret = get_clk(pdev, &mdp5_kms->src_clk, "core_clk_src");
+        ret = get_clk(pdev, &mdp5_kms->src_clk, "core_clk_src", true);
         if (ret)
                 goto fail;
-        ret = get_clk(pdev, &mdp5_kms->core_clk, "core_clk");
+        ret = get_clk(pdev, &mdp5_kms->core_clk, "core_clk", true);
         if (ret)
                 goto fail;
-        ret = get_clk(pdev, &mdp5_kms->lut_clk, "lut_clk");
-        if (ret)
-                DBG("failed to get (optional) lut_clk clock");
-        ret = get_clk(pdev, &mdp5_kms->vsync_clk, "vsync_clk");
+        ret = get_clk(pdev, &mdp5_kms->vsync_clk, "vsync_clk", true);
         if (ret)
                 goto fail;
 
+        /* optional clocks: */
+        get_clk(pdev, &mdp5_kms->lut_clk, "lut_clk", false);
+
         /* we need to set a default rate before enabling.  Set a safe
          * rate first, then figure out hw revision, and then set a
          * more optimal rate: