linux-kernel - RE: [PATCH v6] clk: starfive: jh7110-sys: Fix lower rate of CPUfreq by setting PLL0 rate to 1.5GHz

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Message-ID:
 <NTZPR01MB0956ABB5D9B0D087E085EF8B9F882@NTZPR01MB0956.CHNPR01.prod.partner.outlook.cn>
Date: Fri, 23 Aug 2024 08:34:55 +0000
From: Xingyu Wu <xingyu.wu@...rfivetech.com>
To: Hal Feng <hal.feng@...rfivetech.com>, Conor Dooley <conor@...nel.org>
CC: Emil Renner Berthing <emil.renner.berthing@...onical.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>, Michael Turquette
	<mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>
Subject: RE: [PATCH v6] clk: starfive: jh7110-sys: Fix lower rate of CPUfreq
 by setting PLL0 rate to 1.5GHz

On 23.08.24 11:42, Hal Feng wrote:
> > > >
> > > > I'm still not a fan of hardcoding cpu frequencies in the driver.
> > > > You've added the notifiers exactly so that we can use the standard
> > > > device
> > tree settings for this.
> > > >
> > > > In other words I much prefer v5 of this patchset.
> > > >
> > > > /Emil
> > > >
> > >
> > > Thanks, Emil.
> > >
> > > Hi Conor, what do you think about this issue?
> >
> > Apologies for the delay replying, I didn't realise there was a
> > question here directed at me. My only real thought on the patchset is
> > that what is done should not cause problems when the same devicetree
> > is used for both U-Boot and for the kernel. As long as that's
> > satisfied, I don't mind how you choose to implement it.
> 
> Actually VF2 U-Boot can run at 1.5GHz. It will work if the PMIC sets the CPU
> power supply voltage to 1.04V. The reason why we run VF2 U-Boot at 1.0GHz is
> that the default voltage supplied by the PMIC is 0.9V which only supports JH7110
> cores running at 1.0GHz.
> 
> So v5 of this patchset won't cause problems if the VF2 U-Boot makes some
> changes to support running at 1.5GHz. And I will make these changes when I
> implement OF_UPSTREAM for VF2 U-Boot.
> 
> BTW, if v5 is applied, the patch 2 of v5 should be rebased on the new mainline
> since jh7110-common.dtsi has been created.
> 

Good news. Thanks Hal.

Hi Conor, 

According to Hal, U-Boot can also run 1.5G so that the dts from kernel can be used on the U-Boot and could not cause any problems. So the way of Patch v5[1] works which Emil agreed.
[1]: https://lore.kernel.org/all/20240507065319.274976-1-xingyu.wu@starfivetech.com/

If you agree, I will submit a new patchset soon and modify it for the new jh7110-common.dtsi.

Best regards,
Xingyu Wu