Re: [PATCH v5 08/18] thermal: sun8i: support mod clocks

[Vasily Khoruzhick]

On Fri, Aug 9, 2019 at 10:31 PM Yangtao Li <tiny.windzz@xxxxxxxxx> wrote:
>
> H3 has extra clock, so introduce something in ths_thermal_chip/ths_device
> and adds the process of the clock.
>
> This is pre-work for supprt it.
>
> Signed-off-by: Yangtao Li <tiny.windzz@xxxxxxxxx>
> ---
>  drivers/thermal/sun8i_thermal.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/thermal/sun8i_thermal.c b/drivers/thermal/sun8i_thermal.c
> index b934bc81eba7..6f4294c2aba7 100644
> --- a/drivers/thermal/sun8i_thermal.c
> +++ b/drivers/thermal/sun8i_thermal.c
> @@ -54,6 +54,7 @@ struct tsensor {
>  };
>
>  struct ths_thermal_chip {
> +       bool            has_mod_clk;
>         int             sensor_num;
>         int             offset;
>         int             scale;
> @@ -69,6 +70,7 @@ struct ths_device {
>         struct regmap                           *regmap;
>         struct reset_control                    *reset;
>         struct clk                              *bus_clk;
> +       struct clk                              *mod_clk;
>         struct tsensor                          sensor[MAX_SENSOR_NUM];
>  };
>
> @@ -274,6 +276,12 @@ static int sun8i_ths_resource_init(struct ths_device *tmdev)
>         if (IS_ERR(tmdev->bus_clk))
>                 return PTR_ERR(tmdev->bus_clk);
>
> +       if (tmdev->chip->has_mod_clk) {
> +               tmdev->mod_clk = devm_clk_get(&pdev->dev, "mod");
> +               if (IS_ERR(tmdev->mod_clk))
> +                       return PTR_ERR(tmdev->mod_clk);
> +       }
> +
>         ret = reset_control_deassert(tmdev->reset);
>         if (ret)
>                 return ret;
> @@ -282,12 +290,18 @@ static int sun8i_ths_resource_init(struct ths_device *tmdev)
>         if (ret)
>                 goto assert_reset;
>
> -       ret = sun50i_ths_calibrate(tmdev);
> +       ret = clk_prepare_enable(tmdev->mod_clk);

You have to set rate of modclk before enabling it since you can't rely
on whatever bootloader left for you.

Also I found that parameters you're using for PC_TEMP_PERIOD, ACQ0 and
ACQ1 are too aggressive and may result in high interrupt rate to the
point when it may stall RCU. I changed driver a bit to use params from
Philipp Rossak's work (modclk set to 4MHz, PC_TEMP_PERIOD is 7, ACQ0
is 255, ACQ1 is 63) and it fixed RCU stalls for me, see [1] for
details.

[1] https://github.com/anarsoul/linux-2.6/commit/46b8bb0fe2ccd1cd88fa9181a2ecbf79e8d513b2


>         if (ret)
>                 goto bus_disable;
>
> +       ret = sun50i_ths_calibrate(tmdev);
> +       if (ret)
> +               goto mod_disable;
> +
>         return 0;
>
> +mod_disable:
> +       clk_disable_unprepare(tmdev->mod_clk);
>  bus_disable:
>         clk_disable_unprepare(tmdev->bus_clk);
>  assert_reset:
> @@ -395,6 +409,7 @@ static int sun8i_ths_remove(struct platform_device *pdev)
>  {
>         struct ths_device *tmdev = platform_get_drvdata(pdev);
>
> +       clk_disable_unprepare(tmdev->mod_clk);
>         clk_disable_unprepare(tmdev->bus_clk);
>         reset_control_assert(tmdev->reset);
>
> --
> 2.17.1
>
>
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