On Thu, Nov 21, 2019 at 08:58:59PM +0100, Clément Péron wrote:
> From: Jernej Skrabec <[email protected]>
> 
> H6 PWM core needs bus clock to be enabled in order to work.
> 
> Add an optional probe for it.
> 
> Signed-off-by: Jernej Skrabec <[email protected]>
> Signed-off-by: Clément Péron <[email protected]>
> ---
>  drivers/pwm/pwm-sun4i.c | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
> index 369990ae7d09..66befd8d6f9c 100644
> --- a/drivers/pwm/pwm-sun4i.c
> +++ b/drivers/pwm/pwm-sun4i.c
> @@ -78,6 +78,7 @@ struct sun4i_pwm_data {
>  
>  struct sun4i_pwm_chip {
>       struct pwm_chip chip;
> +     struct clk *bus_clk;
>       struct clk *clk;
>       struct reset_control *rst;
>       void __iomem *base;
> @@ -391,6 +392,14 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
>               }
>       }
>  
> +     pwm->bus_clk = devm_clk_get_optional(&pdev->dev, "bus");
> +     if (IS_ERR(pwm->bus_clk)) {
> +             if (PTR_ERR(pwm->rst) != -EPROBE_DEFER)
> +                     dev_err(&pdev->dev, "get bus clock failed %pe\n",
> +                             pwm->bus_clk);
> +             return PTR_ERR(pwm->bus_clk);
> +     }
> +
>       pwm->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
>       if (IS_ERR(pwm->rst)) {
>               if (PTR_ERR(pwm->rst) != -EPROBE_DEFER)
> @@ -407,6 +416,17 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
>               return ret;
>       }
>  
> +     /*
> +      * We're keeping the bus clock on for the sake of simplicity.
> +      * Actually it only needs to be on for hardware register accesses.
> +      */
> +     ret = clk_prepare_enable(pwm->bus_clk);
> +     if (ret) {
> +             dev_err(&pdev->dev, "Cannot prepare and enable bus_clk %d\n",
> +                     ret);

nitpick: other error messages in this driver start with a lower case
letter.

Until there is an equivalent for %pe that consumes an int, I suggest to
use

        dev_err(&pdev->dev, "Cannot prepare and enable bus_clk: %pe\n",
                ERR_PTR(ret));

to benefit from a symbolic error name instead of an error constant.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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