clk: qcom: mdss: update PLL resources based on ref count

At present, the PLL resources are updated based on the
enable/disable parameter that is passed to the API. Add
support to update the PLL resources based on a ref count.
This avoids additional delay due to repeated enable/disable
of the resources and also maintains proper state of the PLL
resources.

Change-Id: I39b7ee2b33acb81acdb7dc1f4f387dc71381a464
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>

drivers/clk/msm/mdss/mdss-pll.c

@@ -29,6 +29,7 @@
 int mdss_pll_resource_enable(struct mdss_pll_resources *pll_res, bool enable)
 {
 	int rc = 0;
+	int changed = 0;
 	if (!pll_res) {
 		pr_err("Invalid input parameters\n");
 		return -EINVAL;
@@ -44,11 +45,27 @@ int mdss_pll_resource_enable(struct mdss_pll_resources *pll_res, bool enable)
 		return rc;
 	}
 
-	rc = mdss_pll_util_resource_enable(pll_res, enable);
-	if (rc)
-		pr_err("Resource update failed rc=%d\n", rc);
-	else
-		pll_res->resource_enable = enable;
+	if (enable) {
+		if (pll_res->resource_ref_cnt == 0)
+			changed++;
+		pll_res->resource_ref_cnt++;
+	} else {
+		if (pll_res->resource_ref_cnt) {
+			pll_res->resource_ref_cnt--;
+			if (pll_res->resource_ref_cnt == 0)
+				changed++;
+		} else {
+			pr_err("PLL Resources already OFF\n");
+		}
+	}
+
+	if (changed) {
+		rc = mdss_pll_util_resource_enable(pll_res, enable);
+		if (rc)
+			pr_err("Resource update failed rc=%d\n", rc);
+		else
+			pll_res->resource_enable = enable;
+	}
 
 	return rc;
 }

drivers/clk/msm/mdss/mdss-pll.h

@@ -60,6 +60,9 @@ struct mdss_pll_resources {
 	/* HW recommended delay during configuration of vco clock rate */
 	u32		vco_delay;
 
+	/* Ref-count of the PLL resources */
+	u32		resource_ref_cnt;
+
 	/*
 	 * Keep track to resource status to avoid updating same status for the
 	 * pll from different paths