[PATCH v2] arm64: dts: imx8mp: Add DT nodes for the two ISPs

[Marek Vasut]

On 6/11/24 3:04 AM, Peng Fan wrote:
>> Subject: Re: [PATCH v2] arm64: dts: imx8mp: Add DT nodes for the two ISPs
>>>>
>>>>> Something like
>>>>> ---8<---
>>>>> --- a/arch/arm64/boot/dts/freescale/imx8mp.dtsi
>>>>> +++ b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
>>>>> @@ -1837,11 +1837,13 @@ media_blk_ctrl: blk-ctrl at 32ec0000 {
>>>>>                                                    <&clk IMX8MP_CLK_MEDIA_APB>,
>>>>>                                                    <&clk IMX8MP_CLK_MEDIA_DISP1_PIX>,
>>>>>                                                    <&clk
>>>>> IMX8MP_CLK_MEDIA_DISP2_PIX>,
>>>>> +                                                 <&clk
>>>>> + IMX8MP_CLK_MEDIA_ISP>,
>>>>>                                                    <&clk IMX8MP_VIDEO_PLL1>;
>>>>>                                  assigned-clock-parents = <&clk
>> IMX8MP_SYS_PLL2_1000M>,
>>>>>                                                           <&clk IMX8MP_SYS_PLL1_800M>,
>>>>>                                                           <&clk IMX8MP_VIDEO_PLL1_OUT>,
>>>>> -                                                        <&clk IMX8MP_VIDEO_PLL1_OUT>;
>>>>> +                                                        <&clk IMX8MP_VIDEO_PLL1_OUT>,
>>>>> +                                                        <&clk
>>>>> + IMX8MP_SYS_PLL2_500M>;
>>>>>                                  assigned-clock-rates = <500000000>, <200000000>,
>>>>>                                                         <0>, <0>,
>>>>> <1039500000>;
>>>>
>>
>> According to the i.MX8MP Data sheet, the nominal speed for
>> MEDIA_ISP_CLOCL_ROOT is 400MHZ with 500MHz being allowed in
>> overdrive mode.
>>
>> I think this clock rate should drop to  the nominal value of 400MHz and those
>> boards who support overdrive can increase it to 500MHz to avoid stiability
>> issues and/or running out of spec.  I created an imx8mm and imx8mn-
>> overdrive.dtsi file.  If there is interest, I can do the same for the 8MP as well.
>>
>> I haven't gone through all the clocks to determine if/what clocks are being
>> overdriven.
> 
> Shouldn't the bootloader take the work to runtime update the freq?
> Why need introduce an extra overdrive.dtsi?

Shouldn't the overdrive/non-overdrive decision be done in board DT instead ?