disp: msm: dp: park pixel clock before disable

When switching between 2 dongles/adapters it is possible
to have the same resolution with different link configuration.
Even though the pixel clock could be the same on replug, the
vco clock could be different depending on the link
configuration. Since the dp driver only exposes limited clocks
to the clock framework, in this specific scenario, the clock
driver is unable to recognize the change in source clock rate
and ends up skipping the clock reconfiguration.

This change adds support to park the pixel clocks on disable,
thereby forcing a reconfiguration on subsequent replug even
if the pixel clocks are the same.

Change-Id: If90b37d6285f6cad23cf1c11a7d6ccd6b4cf850c
Signed-off-by: Rajkumar Subbiah <quic_rsubbia@quicinc.com>

msm/dp/dp_power.c

@@ -11,6 +11,7 @@
 #include "dp_pll.h"
 
 #define DP_CLIENT_NAME_SIZE	20
+#define XO_CLK_KHZ	19200
 
 struct dp_power_private {
 	struct dp_parser *parser;
@@ -19,6 +20,7 @@ struct dp_power_private {
 	struct clk *pixel_clk_rcg;
 	struct clk *pixel_parent;
 	struct clk *pixel1_clk_rcg;
+	struct clk *xo_clk;
 
 	struct dp_power dp_power;
 
@@ -26,6 +28,8 @@ struct dp_power_private {
 	bool link_clks_on;
 	bool strm0_clks_on;
 	bool strm1_clks_on;
+	bool strm0_clks_parked;
+	bool strm1_clks_parked;
 };
 
 static int dp_power_regulator_init(struct dp_power_private *power)
@@ -220,6 +224,14 @@ static int dp_power_clk_init(struct dp_power_private *power, bool enable)
 			goto err_pixel_parent;
 		}
 
+		power->xo_clk = clk_get(dev, "rpmh_cxo_clk");
+		if (IS_ERR(power->xo_clk)) {
+			DP_ERR("Unable to get XO clk: %d\n", PTR_ERR(power->xo_clk));
+			rc = PTR_ERR(power->xo_clk);
+			power->xo_clk = NULL;
+			goto err_xo_clk;
+		}
+
 		if (power->parser->has_mst) {
 			power->pixel1_clk_rcg = clk_get(dev, "pixel1_clk_rcg");
 			if (IS_ERR(power->pixel1_clk_rcg)) {
@@ -244,8 +256,9 @@ static int dp_power_clk_init(struct dp_power_private *power, bool enable)
 	}
 
 	return rc;
-
 err_pixel1_clk_rcg:
+	clk_put(power->xo_clk);
+err_xo_clk:
 	clk_put(power->pixel_parent);
 err_pixel_parent:
 	clk_put(power->pixel_clk_rcg);
@@ -255,6 +268,59 @@ exit:
 	return rc;
 }
 
+static int dp_power_park_module(struct dp_power_private *power, enum dp_pm_type module)
+{
+	struct dss_module_power *mp;
+	struct clk *clk = NULL;
+	int rc = 0;
+	bool *parked;
+
+	mp = &power->parser->mp[module];
+
+	if (module == DP_STREAM0_PM) {
+		clk = power->pixel_clk_rcg;
+		parked = &power->strm0_clks_parked;
+	} else if (module == DP_STREAM1_PM) {
+		clk = power->pixel1_clk_rcg;
+		parked = &power->strm1_clks_parked;
+	} else {
+		goto exit;
+	}
+
+	if (!clk) {
+		DP_WARN("clk type %d not supported\n", module);
+		rc = -EINVAL;
+		goto exit;
+	}
+
+	if (!power->xo_clk) {
+		rc = -EINVAL;
+		goto exit;
+	}
+
+	if (*parked)
+		goto exit;
+
+	rc = clk_set_parent(clk, power->xo_clk);
+	if (rc) {
+		DP_ERR("unable to set xo parent on clk %d\n", module);
+		goto exit;
+	}
+
+	mp->clk_config->rate = XO_CLK_KHZ;
+	rc = msm_dss_clk_set_rate(mp->clk_config, mp->num_clk);
+	if (rc) {
+		DP_ERR("failed to set clk rate.\n");
+		goto exit;
+	}
+
+	*parked = true;
+
+exit:
+	return rc;
+}
+
+
 static int dp_power_clk_set_rate(struct dp_power_private *power,
 		enum dp_pm_type module, bool enable)
 {
@@ -287,6 +353,8 @@ static int dp_power_clk_set_rate(struct dp_power_private *power,
 			DP_ERR("failed to disable clks\n");
 				goto exit;
 		}
+
+		dp_power_park_module(power, module);
 	}
 exit:
 	return rc;
@@ -367,6 +435,11 @@ static int dp_power_clk_enable(struct dp_power *dp_power,
 	else if (pm_type == DP_LINK_PM)
 		power->link_clks_on = enable;
 
+	if (pm_type == DP_STREAM0_PM)
+		power->strm0_clks_parked = false;
+	if (pm_type == DP_STREAM1_PM)
+		power->strm1_clks_parked = false;
+
 	/*
 	 * This log is printed only when user connects or disconnects
 	 * a DP cable. As this is a user-action and not a frequent
@@ -581,6 +654,34 @@ static void dp_power_client_deinit(struct dp_power *dp_power)
 	dp_power_regulator_deinit(power);
 }
 
+static int dp_power_park_clocks(struct dp_power *dp_power)
+{
+	int rc = 0;
+	struct dp_power_private *power;
+
+	if (!dp_power) {
+		DP_ERR("invalid power data\n");
+		return -EINVAL;
+	}
+
+	power = container_of(dp_power, struct dp_power_private, dp_power);
+
+	rc = dp_power_park_module(power, DP_STREAM0_PM);
+	if (rc) {
+		DP_ERR("failed to park stream 0. err=%d\n", rc);
+		goto error;
+	}
+
+	rc = dp_power_park_module(power, DP_STREAM1_PM);
+	if (rc) {
+		DP_ERR("failed to park stream 1. err=%d\n", rc);
+		goto error;
+	}
+
+error:
+	return rc;
+}
+
 static int dp_power_set_pixel_clk_parent(struct dp_power *dp_power, u32 strm_id)
 {
 	int rc = 0;
@@ -764,6 +865,7 @@ struct dp_power *dp_power_get(struct dp_parser *parser, struct dp_pll *pll)
 	dp_power->clk_enable = dp_power_clk_enable;
 	dp_power->clk_status = dp_power_clk_status;
 	dp_power->set_pixel_clk_parent = dp_power_set_pixel_clk_parent;
+	dp_power->park_clocks = dp_power_park_clocks;
 	dp_power->clk_get_rate = dp_power_clk_get_rate;
 	dp_power->power_client_init = dp_power_client_init;
 	dp_power->power_client_deinit = dp_power_client_deinit;