Re: [PATCH V4 11/11] clk: imx: lpcg: add suspend/resume support

[Stephen Boyd <sboyd@kernel.org>]

Quoting Dong Aisheng (2019-08-20 04:13:25)
> diff --git a/drivers/clk/imx/clk-lpcg-scu.c b/drivers/clk/imx/clk-lpcg-scu.c
> index 3c092a0..4df0818 100644
> --- a/drivers/clk/imx/clk-lpcg-scu.c
> +++ b/drivers/clk/imx/clk-lpcg-scu.c
> @@ -33,6 +33,9 @@ struct clk_lpcg_scu {
>         void __iomem *reg;
>         u8 bit_idx;
>         bool hw_gate;
> +
> +       /* for state save&restore */
> +       u32 state;
>  };
>  
>  #define to_clk_lpcg_scu(_hw) container_of(_hw, struct clk_lpcg_scu, hw)
> @@ -112,5 +115,35 @@ struct clk_hw *__imx_clk_lpcg_scu(struct device *dev, const char *name,
>                 hw = ERR_PTR(ret);
>         }
>  
> +       if (dev)
> +               dev_set_drvdata(dev, clk);
> +
>         return hw;
>  }
> +
> +int __maybe_unused imx_clk_lpcg_scu_suspend(struct device *dev)

static?

> +{
> +       struct clk_lpcg_scu *clk = dev_get_drvdata(dev);
> +
> +       clk->state = readl_relaxed(clk->reg);
> +       dev_dbg(dev, "save lpcg state 0x%x\n", clk->state);
> +
> +       return 0;
> +}
> +
> +int __maybe_unused imx_clk_lpcg_scu_resume(struct device *dev)

static?

> +{
> +       struct clk_lpcg_scu *clk = dev_get_drvdata(dev);
> +
> +       /* FIXME: double write in case a failure */
 
What does this mean? Sometimes writes don't work unless the CPU issues
them twice?

> +       writel(clk->state, clk->reg);
> +       writel(clk->state, clk->reg);
> +       dev_dbg(dev, "restore lpcg state 0x%x\n", clk->state);
> +
> +       return 0;
> +}
> +
> +const struct dev_pm_ops imx_clk_lpcg_scu_pm_ops = {
> +       SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(imx_clk_lpcg_scu_suspend,
> +                                     imx_clk_lpcg_scu_resume)
> +};