linux-kernel - [PATCH 1/8] clk: imx95-blk-ctl: Cache registers when RPM routines are called

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Message-Id: <20250709122332.2874632-2-laurentiu.palcu@oss.nxp.com>
Date: Wed,  9 Jul 2025 15:23:20 +0300
From: Laurentiu Palcu <laurentiu.palcu@....nxp.com>
To: imx@...ts.linux.dev,
	Abel Vesa <abelvesa@...nel.org>,
	Peng Fan <peng.fan@....com>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>
Cc: dri-devel@...ts.freedesktop.org,
	Laurentiu Palcu <laurentiu.palcu@....nxp.com>,
	Abel Vesa <abel.vesa@...aro.org>,
	linux-clk@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/8] clk: imx95-blk-ctl: Cache registers when RPM routines are called

If runtime PM is used for the clock providers and they're part of a
power domain, then the power domain supply will be cut off when runtime
suspended. That means all BLK CTL registers belonging to that power
domain will be reset. Hence, the clock settings will revert to default
values messing up the consumer clock settings.

Also, fix the suspend/resume routines as well, as the clock was left ON
when going to suspend.

Fixes: 5224b189462f ("clk: imx: add i.MX95 BLK CTL clk driver")
Signed-off-by: Laurentiu Palcu <laurentiu.palcu@....nxp.com>
---
 drivers/clk/imx/clk-imx95-blk-ctl.c | 55 ++++++++++++++++++-----------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/drivers/clk/imx/clk-imx95-blk-ctl.c b/drivers/clk/imx/clk-imx95-blk-ctl.c
index 7e88877a62451..7f9bbca517284 100644
--- a/drivers/clk/imx/clk-imx95-blk-ctl.c
+++ b/drivers/clk/imx/clk-imx95-blk-ctl.c
@@ -448,12 +448,36 @@ static int imx95_bc_probe(struct platform_device *pdev)
 	return ret;
 }
 
+static void __maybe_unused imx95_bc_save_reg(struct imx95_blk_ctl *bc)
+{
+	const struct imx95_blk_ctl_dev_data *bc_data;
+
+	bc_data = of_device_get_match_data(bc->dev);
+	if (!bc_data)
+		return;
+
+	bc->clk_reg_restore = readl(bc->base + bc_data->clk_reg_offset);
+}
+
+static void __maybe_unused imx95_bc_restore_reg(struct imx95_blk_ctl *bc)
+{
+	const struct imx95_blk_ctl_dev_data *bc_data;
+
+	bc_data = of_device_get_match_data(bc->dev);
+	if (!bc_data)
+		return;
+
+	writel(bc->clk_reg_restore, bc->base + bc_data->clk_reg_offset);
+}
+
 #ifdef CONFIG_PM
 static int imx95_bc_runtime_suspend(struct device *dev)
 {
 	struct imx95_blk_ctl *bc = dev_get_drvdata(dev);
 
+	imx95_bc_save_reg(bc);
 	clk_disable_unprepare(bc->clk_apb);
+
 	return 0;
 }
 
@@ -461,7 +485,10 @@ static int imx95_bc_runtime_resume(struct device *dev)
 {
 	struct imx95_blk_ctl *bc = dev_get_drvdata(dev);
 
-	return clk_prepare_enable(bc->clk_apb);
+	clk_prepare_enable(bc->clk_apb);
+	imx95_bc_restore_reg(bc);
+
+	return 0;
 }
 #endif
 
@@ -469,22 +496,12 @@ static int imx95_bc_runtime_resume(struct device *dev)
 static int imx95_bc_suspend(struct device *dev)
 {
 	struct imx95_blk_ctl *bc = dev_get_drvdata(dev);
-	const struct imx95_blk_ctl_dev_data *bc_data;
-	int ret;
 
-	bc_data = of_device_get_match_data(dev);
-	if (!bc_data)
+	if (pm_runtime_suspended(dev))
 		return 0;
 
-	if (bc_data->rpm_enabled) {
-		ret = pm_runtime_get_sync(bc->dev);
-		if (ret < 0) {
-			pm_runtime_put_noidle(bc->dev);
-			return ret;
-		}
-	}
-
-	bc->clk_reg_restore = readl(bc->base + bc_data->clk_reg_offset);
+	imx95_bc_save_reg(bc);
+	clk_disable_unprepare(bc->clk_apb);
 
 	return 0;
 }
@@ -492,16 +509,12 @@ static int imx95_bc_suspend(struct device *dev)
 static int imx95_bc_resume(struct device *dev)
 {
 	struct imx95_blk_ctl *bc = dev_get_drvdata(dev);
-	const struct imx95_blk_ctl_dev_data *bc_data;
 
-	bc_data = of_device_get_match_data(dev);
-	if (!bc_data)
+	if (pm_runtime_suspended(dev))
 		return 0;
 
-	writel(bc->clk_reg_restore, bc->base + bc_data->clk_reg_offset);
-
-	if (bc_data->rpm_enabled)
-		pm_runtime_put(bc->dev);
+	clk_prepare_enable(bc->clk_apb);
+	imx95_bc_restore_reg(bc);
 
 	return 0;
 }
-- 
2.46.1