Re: [PATCH v2 1/7] pwm: rockchip: Add APB and function both clocks support

[David.Wu]

Hi Doug,

å 2017/7/12 1:03, Doug Anderson åé:
> Hi,
>
> On Fri, Jul 7, 2017 at 9:03 PM, David Wu <david.wu@xxxxxxxxxxxxxx> wrote:
>
> > @@ -6,7 +6,13 @@ Required properties:
> >      "rockchip,rk3288-pwm": found on RK3288 SoC
> >      "rockchip,vop-pwm": found integrated in VOP on RK3288 SoC
> >    - reg: physical base address and length of the controller's registers
> > - - clocks: phandle and clock specifier of the PWM reference clock
> > + - clocks: See ../clock/clock-bindings.txt
> > +   - For older hardware (rk2928, rk3066, rk3188, rk3228, rk3288, rk3399):
> > +     - There is one clock that's used both to derive the functional clock
> > +       for the device and as the bus clock.
> > +   - For newer hardware (rk3328 and future socs): specified by name
> > +     - "pwm": This is used to derive the functional clock.
> > +     - "pclk": This is the APB bus clock.
>
> I'm pretty sure that that the above description doesn't quite match the code.
>
> * The above description says that for old hardware there is one clock
> and 'clock-names' was not necessary (though as I understand it it's OK
> if it's there).
>
> * The old code matched the old description.  AKA: if there was no
> "clock-names" then everything was OK.
>
> * The new code will not work if there was no "clock-names".
>
> Many of the old devices had a clock-names present (and it was "pwm"),
> but not all.  Specifically it looks like
> "arch/arm/boot/dts/rk3xxx.dtsi" doesn't specify a clock-names.

So we can keep code: the pc->clk = devm_clk_get(&pdev->dev, NULL);
If the name is NULL, we can get the first clk defined at DTB.

> > @@ -343,13 +344,38 @@ static int rockchip_pwm_probe(struct platform_device *pdev)
> >          if (IS_ERR(pc->base))
> >                  return PTR_ERR(pc->base);
> >
> > -       pc->clk = devm_clk_get(&pdev->dev, NULL);
> > -       if (IS_ERR(pc->clk))
> > -               return PTR_ERR(pc->clk);
> > +       pc->clk = devm_clk_get(&pdev->dev, "pwm");
> > +       count = of_property_count_strings(pdev->dev.of_node, "clock-names");
> > +       if (count == 2)
> > +               pc->pclk = devm_clk_get(&pdev->dev, "pclk");
> > +       else
> > +               pc->pclk = pc->clk;
> > +
> > +       if (IS_ERR(pc->clk)) {
> > +               ret = PTR_ERR(pc->clk);
> > +               if (ret != -EPROBE_DEFER)
> > +                       dev_err(&pdev->dev, "Can't get bus clk: %d\n", ret);
> > +               return ret;
> > +       }
> > +
> > +       if (IS_ERR(pc->pclk)) {
> > +               ret = PTR_ERR(pc->pclk);
> > +               if (ret != -EPROBE_DEFER)
> > +                       dev_err(&pdev->dev, "Can't get APB clk: %d\n", ret);
> > +               return ret;
> > +       }
>
> In the above code you need to check the count _before_ trying to get
> the clock by name.

Okay, I will fix it.

> -Doug