OMAPDSS: setup default dss fck

We don't currently set the dss fck when starting up. This is not a
problem, as we setup the fck later when configuring the pixel clocks. Or
this is how it was for omap2, for the rest of the omaps this may not be
so.

For DSI, HDMI and also for DPI when using DSI PLL, we don't need to
change the dss fck, and thus it may be left unconfigured. Usually the
dss fck is already setup fine by default, but we can't trust this.

This patch sets the dss fck to maximum at probe time.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/omap2/dss/dss.c

@@ -485,6 +485,36 @@ unsigned long dss_get_dpll4_rate(void)
 		return 0;
 }
 
+static int dss_setup_default_clock(void)
+{
+	unsigned long max_dss_fck, prate;
+	unsigned fck_div;
+	struct dss_clock_info dss_cinfo = { 0 };
+	int r;
+
+	if (dss.dpll4_m4_ck == NULL)
+		return 0;
+
+	max_dss_fck = dss_feat_get_param_max(FEAT_PARAM_DSS_FCK);
+
+	prate = dss_get_dpll4_rate();
+
+	fck_div = DIV_ROUND_UP(prate * dss.feat->dss_fck_multiplier,
+			max_dss_fck);
+
+	dss_cinfo.fck_div = fck_div;
+
+	r = dss_calc_clock_rates(&dss_cinfo);
+	if (r)
+		return r;
+
+	r = dss_set_clock_div(&dss_cinfo);
+	if (r)
+		return r;
+
+	return 0;
+}
+
 int dss_calc_clock_div(unsigned long req_pck, struct dss_clock_info *dss_cinfo,
 		struct dispc_clock_info *dispc_cinfo)
 {
@@ -892,6 +922,10 @@ static int __init omap_dsshw_probe(struct platform_device *pdev)
 	if (r)
 		return r;
 
+	r = dss_setup_default_clock();
+	if (r)
+		goto err_setup_clocks;
+
 	pm_runtime_enable(&pdev->dev);
 
 	r = dss_runtime_get();
@@ -924,6 +958,7 @@ static int __init omap_dsshw_probe(struct platform_device *pdev)
 
 err_runtime_get:
 	pm_runtime_disable(&pdev->dev);
+err_setup_clocks:
 	dss_put_clocks();
 	return r;
 }