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SubjectRe: [PATCH v2 1/7] pwm: rockchip: Add APB and function both clocks support
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Hi Doug,

在 2017/7/12 1:03, Doug Anderson 写道:
> Hi,
>
> On Fri, Jul 7, 2017 at 9:03 PM, David Wu <david.wu@rock-chips.com> 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
>
>
>

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