Subject:
save and store registers at suspend()/resume() function
On Wed, Jul 09, 2025 at 03:23:20PM +0300, Laurentiu Palcu wrote:
> 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.
Needn't "hence ..."
Save/restore register value at suspend/resume functions to fix this problem.
>
> Also, fix the suspend/resume routines as well, as the clock was left ON
> when going to suspend.
Do you means fix the problem clock left ON after suspend?
Pomain cut off, why clock can left on?
>
> Fixes: 5224b189462f ("clk: imx: add i.MX95 BLK CTL clk driver")
> Signed-off-by: Laurentiu Palcu <[email protected]>
> ---
> 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);
Generally, bc_data should in imx95_blk_ctl_dev_data and set once at probe.
So imx95_bc_save_reg() and imx95_bc_restore_reg() will be simpfied.
> + 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);
this help function just one line. direct use
writel(bc->clk_reg_restore, bc->base + bc->bc_data->clk_reg_offset);
> 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);
Need check ret value;
> + 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;
> }
look like imx95_bc_suspend(resume) is simple enough
Can you use DEFINE_RUNTIME_DEV_PM_OPS?
Frank
> --
> 2.46.1
>
