drm/stm: dsi: add pm runtime ops

Update control of clocks and supply thanks to the PM runtime
mechanism to avoid kernel crash during a system suspend.
Signed-off-by: Yannick Fertre <yannick.fertre@foss.st.com>
Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
Acked-by: Yannick Fertre <yannick.fertre@foss.st.com>
Tested-by: Yannick Fertre <yannick.fertre@foss.st.com>
Signed-off-by: Philippe Cornu <philippe.cornu@foss.st.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240129104106.43141-3-raphael.gallais-pou@foss.st.com

drivers/gpu/drm/stm/dw_mipi_dsi-stm.c

@@ -11,6 +11,7 @@
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>
 
 #include <video/mipi_display.h>
@@ -77,6 +78,7 @@ enum dsi_color {
 struct dw_mipi_dsi_stm {
 	void __iomem *base;
 	struct clk *pllref_clk;
+	struct clk *pclk;
 	struct dw_mipi_dsi *dsi;
 	u32 hw_version;
 	int lane_min_kbps;
@@ -443,7 +445,6 @@ static int dw_mipi_dsi_stm_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct dw_mipi_dsi_stm *dsi;
-	struct clk *pclk;
 	int ret;
 
 	dsi = devm_kzalloc(dev, sizeof(*dsi), GFP_KERNEL);
@@ -483,21 +484,21 @@ static int dw_mipi_dsi_stm_probe(struct platform_device *pdev)
 		goto err_clk_get;
 	}
 
-	pclk = devm_clk_get(dev, "pclk");
-	if (IS_ERR(pclk)) {
-		ret = PTR_ERR(pclk);
+	dsi->pclk = devm_clk_get(dev, "pclk");
+	if (IS_ERR(dsi->pclk)) {
+		ret = PTR_ERR(dsi->pclk);
 		DRM_ERROR("Unable to get peripheral clock: %d\n", ret);
 		goto err_dsi_probe;
 	}
 
-	ret = clk_prepare_enable(pclk);
+	ret = clk_prepare_enable(dsi->pclk);
 	if (ret) {
 		DRM_ERROR("%s: Failed to enable peripheral clk\n", __func__);
 		goto err_dsi_probe;
 	}
 
 	dsi->hw_version = dsi_read(dsi, DSI_VERSION) & VERSION;
-	clk_disable_unprepare(pclk);
+	clk_disable_unprepare(dsi->pclk);
 
 	if (dsi->hw_version != HWVER_130 && dsi->hw_version != HWVER_131) {
 		ret = -ENODEV;
@@ -551,6 +552,7 @@ static int dw_mipi_dsi_stm_suspend(struct device *dev)
 	DRM_DEBUG_DRIVER("\n");
 
 	clk_disable_unprepare(dsi->pllref_clk);
+	clk_disable_unprepare(dsi->pclk);
 	regulator_disable(dsi->vdd_supply);
 
 	return 0;
@@ -569,8 +571,16 @@ static int dw_mipi_dsi_stm_resume(struct device *dev)
 		return ret;
 	}
 
+	ret = clk_prepare_enable(dsi->pclk);
+	if (ret) {
+		regulator_disable(dsi->vdd_supply);
+		DRM_ERROR("Failed to enable pclk: %d\n", ret);
+		return ret;
+	}
+
 	ret = clk_prepare_enable(dsi->pllref_clk);
 	if (ret) {
+		clk_disable_unprepare(dsi->pclk);
 		regulator_disable(dsi->vdd_supply);
 		DRM_ERROR("Failed to enable pllref_clk: %d\n", ret);
 		return ret;
@@ -582,6 +592,8 @@ static int dw_mipi_dsi_stm_resume(struct device *dev)
 static const struct dev_pm_ops dw_mipi_dsi_stm_pm_ops = {
 	SYSTEM_SLEEP_PM_OPS(dw_mipi_dsi_stm_suspend,
 			    dw_mipi_dsi_stm_resume)
+	RUNTIME_PM_OPS(dw_mipi_dsi_stm_suspend,
+		       dw_mipi_dsi_stm_resume, NULL)
 };
 
 static struct platform_driver dw_mipi_dsi_stm_driver = {