drm: atmel-hlcdc: enable sys_clk during initalization.

For SAM9X60 SoC, sys_clk is through lcd_gclk clock source and this
needs to be enabled before enabling lcd_clk.
Signed-off-by: Sandeep Sheriker Mallikarjun <sandeepsheriker.mallikarjun@microchip.com>
[claudiu.beznea@microchip.com: add fixed_clksrc checks]
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1556195748-11106-5-git-send-email-claudiu.beznea@microchip.com

drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c

@@ -625,10 +625,18 @@ static int atmel_hlcdc_dc_load(struct drm_device *dev)
 	dc->hlcdc = dev_get_drvdata(dev->dev->parent);
 	dev->dev_private = dc;
 
+	if (dc->desc->fixed_clksrc) {
+		ret = clk_prepare_enable(dc->hlcdc->sys_clk);
+		if (ret) {
+			dev_err(dev->dev, "failed to enable sys_clk\n");
+			goto err_destroy_wq;
+		}
+	}
+
 	ret = clk_prepare_enable(dc->hlcdc->periph_clk);
 	if (ret) {
 		dev_err(dev->dev, "failed to enable periph_clk\n");
-		goto err_destroy_wq;
+		goto err_sys_clk_disable;
 	}
 
 	pm_runtime_enable(dev->dev);
@@ -664,6 +672,9 @@ static int atmel_hlcdc_dc_load(struct drm_device *dev)
 err_periph_clk_disable:
 	pm_runtime_disable(dev->dev);
 	clk_disable_unprepare(dc->hlcdc->periph_clk);
+err_sys_clk_disable:
+	if (dc->desc->fixed_clksrc)
+		clk_disable_unprepare(dc->hlcdc->sys_clk);
 
 err_destroy_wq:
 	destroy_workqueue(dc->wq);
@@ -688,6 +699,8 @@ static void atmel_hlcdc_dc_unload(struct drm_device *dev)
 
 	pm_runtime_disable(dev->dev);
 	clk_disable_unprepare(dc->hlcdc->periph_clk);
+	if (dc->desc->fixed_clksrc)
+		clk_disable_unprepare(dc->hlcdc->sys_clk);
 	destroy_workqueue(dc->wq);
 }
 
@@ -805,6 +818,8 @@ static int atmel_hlcdc_dc_drm_suspend(struct device *dev)
 	regmap_read(regmap, ATMEL_HLCDC_IMR, &dc->suspend.imr);
 	regmap_write(regmap, ATMEL_HLCDC_IDR, dc->suspend.imr);
 	clk_disable_unprepare(dc->hlcdc->periph_clk);
+	if (dc->desc->fixed_clksrc)
+		clk_disable_unprepare(dc->hlcdc->sys_clk);
 
 	return 0;
 }
@@ -814,6 +829,8 @@ static int atmel_hlcdc_dc_drm_resume(struct device *dev)
 	struct drm_device *drm_dev = dev_get_drvdata(dev);
 	struct atmel_hlcdc_dc *dc = drm_dev->dev_private;
 
+	if (dc->desc->fixed_clksrc)
+		clk_prepare_enable(dc->hlcdc->sys_clk);
 	clk_prepare_enable(dc->hlcdc->periph_clk);
 	regmap_write(dc->hlcdc->regmap, ATMEL_HLCDC_IER, dc->suspend.imr);