linux-kernel - Re: [PATCH v1] clk: starfive: jh7110-sys: Set PLL0 rate to 1.5GHz

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Date:   Mon, 14 Aug 2023 15:28:14 +0800
From:   Xingyu Wu <xingyu.wu@...rfivetech.com>
To:     Conor Dooley <conor.dooley@...rochip.com>
CC:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Emil Renner Berthing <emil.renner.berthing@...onical.com>,
        Conor Dooley <conor@...nel.org>,
        "Hal Feng" <hal.feng@...rfivetech.com>,
        <linux-kernel@...r.kernel.org>, <linux-clk@...r.kernel.org>
Subject: Re: [PATCH v1] clk: starfive: jh7110-sys: Set PLL0 rate to 1.5GHz

On 2023/8/14 14:57, Conor Dooley wrote:
> On Mon, Aug 14, 2023 at 11:06:05AM +0800, Xingyu Wu wrote:
>> On 2023/8/11 14:43, Conor Dooley wrote:
>> > On Fri, Aug 11, 2023 at 11:36:31AM +0800, Xingyu Wu wrote:
>> >> Set PLL0 rate to 1.5GHz.
>> > 
>> > Why are you doing that though?
>> 
>> Because the CPU frequency scaling is based on 1.5GHz rate on JH7110 SoC.
>> And now the PLL clock driver has been accepted and PLL0 is just 1GHz[1].
>> [1] https://github.com/starfive-tech/VisionFive2/issues/55
>> 
>> We should set the PLL0 rate to a correct rate (1.5GHz) and then
>> the CPUfreq will work normally.
> 
> Please include an explanation in the commit message of the problem this
> is addressing.
> 
> Also, a Fixes: tag + reported-by?
> 

OK, I will add the explanation in next version as a fixes patch.

Thanks,
Xingyu Wu

>> > 
>> > 
>> >> Change the parent of cpu_root clock
>> >> and the divider of cpu_core before setting.
>> >> 
>> >> Signed-off-by: Xingyu Wu <xingyu.wu@...rfivetech.com>
>> >> ---
>> >> 
>> >> Hi Stephen and Emil,
>> >> 
>> >> This patch sets PLL0 rate to 1.5GHz. In order not to affect the cpu 
>> >> operation, the cpu_root's parent clock should be changed first.
>> >> And the divider of the cpu_core clock should be set to 2 so they
>> >> won't crash when setting 1.5GHz without voltage regulation.
>> >> 
>> >> This patch is based on linux-next which has merge PLL driver on
>> >> StarFive JH7110 SoC.
>> >> 
>> >> Thanks,
>> >> Xingyu Wu
>>