Re: [PATCH v2 2/2] clk: imx95-blk-ctl: Save/restore registers when RPM routines are called
From: Frank Li <Frank.li@nxp.com>
Date: 2025-08-05 20:25:22
Also in:
imx, linux-clk, lkml
On Mon, Aug 04, 2025 at 04:14:50PM +0300, Laurentiu Palcu wrote:
When runtime PM is used for clock providers that are part of a power domain, the power domain supply is cut off during runtime suspend. This causes all BLK CTL registers belonging to that power domain to reset. To prevent this, save the state of the registers before entering suspend and restore them on resume. Additionally, disable the APB clock during suspend to minimize power consumption. Signed-off-by: Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
quoted hunk ↗ jump to hunk
--- drivers/clk/imx/clk-imx95-blk-ctl.c | 33 ++++++++++++++++++----------- 1 file changed, 21 insertions(+), 12 deletions(-)diff --git a/drivers/clk/imx/clk-imx95-blk-ctl.c b/drivers/clk/imx/clk-imx95-blk-ctl.c index c72debaf3a60b..56bed44719954 100644 --- a/drivers/clk/imx/clk-imx95-blk-ctl.c +++ b/drivers/clk/imx/clk-imx95-blk-ctl.c@@ -453,15 +453,24 @@ static int imx95_bc_runtime_suspend(struct device *dev) { struct imx95_blk_ctl *bc = dev_get_drvdata(dev); + bc->clk_reg_restore = readl(bc->base + bc->pdata->clk_reg_offset); clk_disable_unprepare(bc->clk_apb); + return 0; } static int imx95_bc_runtime_resume(struct device *dev) { struct imx95_blk_ctl *bc = dev_get_drvdata(dev); + int ret; - return clk_prepare_enable(bc->clk_apb); + ret = clk_prepare_enable(bc->clk_apb); + if (ret) + return ret; + + writel(bc->clk_reg_restore, bc->base + bc->pdata->clk_reg_offset); + + return 0; } #endif@@ -469,17 +478,12 @@ 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); - int ret; - if (bc->pdata->rpm_enabled) { - ret = pm_runtime_get_sync(bc->dev); - if (ret < 0) { - pm_runtime_put_noidle(bc->dev); - return ret; - } - } + if (pm_runtime_suspended(dev)) + return 0; bc->clk_reg_restore = readl(bc->base + bc->pdata->clk_reg_offset); + clk_disable_unprepare(bc->clk_apb); return 0; }@@ -487,11 +491,16 @@ 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); + int ret; - writel(bc->clk_reg_restore, bc->base + bc->pdata->clk_reg_offset); + if (pm_runtime_suspended(dev)) + return 0; - if (bc->pdata->rpm_enabled) - pm_runtime_put(bc->dev); + ret = clk_prepare_enable(bc->clk_apb); + if (ret) + return ret; + + writel(bc->clk_reg_restore, bc->base + bc->pdata->clk_reg_offset); return 0; } --2.49.0