Re: [PATCH] arm64: dts: rockchip: Explicitly set pclk_pmu_src on rk3399

Elaine Zhang
2016-08-30T00:59:31Z

On 08/30/2016 02:18 AM, Brian Norris wrote:
> On Mon, Aug 29, 2016 at 11:11:24AM -0700, Doug Anderson wrote:
>> On rk3399 we explicitly set ppll in the device tree to 676000000. The
>> ppll has one major child, pclk_pmu_src, that is the parent of lots of
>> other clocks. Right now nobody is setting that clock rate and we're
>> relying on the divider to just happen to be something sane. Let's be
>> explicit in our request so we're not relying on the firmware.
>>
>> With the current firmware I tested with this patch has no expected
>> impact but it's probably good to do anyway.
>>
>> Signed-off-by: Douglas Anderson <dianders@chromium.org>
>> ---
>> arch/arm64/boot/dts/rockchip/rk3399.dtsi | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>> index 62d450935a57..ffb3faa8c176 100644
>> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>> @@ -908,8 +908,8 @@
>> reg = <0x0 0xff750000 0x0 0x1000>;
>> #clock-cells = <1>;
>> #reset-cells = <1>;
>> - assigned-clocks = <&pmucru PLL_PPLL>;
>> - assigned-clock-rates = <676000000>;
>> + assigned-clocks = <&pmucru PLL_PPLL>, <&pmucru PCLK_SRC_PMU>;
>> + assigned-clock-rates = <676000000>, <112666667>;
>
> I think this makes sense and is a good idea. One alternative would be to
> have the various children actually set a rate that they expect, but
> several of them don't have a separate driver at all, and that would be
> of dubious value anyway I think.

I agree with you. This clk default div is set in the uboot or coreboot.
And if is need to set in kernel ,I hope the freq is 50M(<48285714>).
This freq can meet the performance,and the power consumption is not too
much.
>
> Reviewed-by: Brian Norris <briannorris@chromium.org>
>
>> };
>>
>> cru: clock-controller@ff760000 {
>> --
>> 2.8.0.rc3.226.g39d4020
>>
>
>
>