Re: 回复: [DMARC error] [PATCH v3 3/3] arm64: dts: meson-s4-s905y4-khadas-vim1s: add initial device tree

[George Stark]

On 2/10/26 01:31, Martin Blumenstingl wrote:
> Hi George,
>
> sorry for the late reply.
>
> On Thu, Jan 29, 2026 at 3:48 PM George Stark <gnstark@xxxxxxxxxxxxxxxxx> wrote:

Hello Martin. It's great to hear from you again.
> > On 1/26/26 12:35, Nick Xie wrote:
> > > > Thanks for the patch. Since you have khadas mail I'm pretty sure you've
> > > > had the possibility to test it on the real vim board and I just don't
> > > > get it how it works with the voltage table above. The problem is that
> > > > pwm is calculated incorrectly in the upstream pwm-meson driver. That
> > > > voltage table appeared to be used in early amlogic bl loader and
> > > > appropriate pwm is initialized from a table's record. Duty cycle value
> > > > is translated to pwm regs correctly. Later when kernel start running
> > > > pwm-regulator driver is probed. It reads the pwm regs, calculates back
> > > > duty-cyle and search it in the table. Since calculation algos are not
> > > > match and the table doesn't contain full range of 0-100% values
> > > > regulator driver doesn't find current voltage. In such case regulator
> > > > core sets the minimum voltage from the table [1] and the SoC may hang
> > > > (depending on board) due to minimum voltage may be too low for the
> > > > current frequency SoC uses.
> Nick likely didn't spot any issues on S4 since CPU frequency scaling
> is not upstreamed yet (as there's no way to control the CPU clock
> yet).
> The lack of a OPP table means: the PWM and CPU clock will just stay at
> whatever the bootloader provides

It makes sense. I should experiment on the latest kernel.

> > > > Or I'm missing something?
> > >
> > >
> > > > There's not-yet-reviewed patch that fixes pwm algo [2]. There's
> > > > calculation example in the cover letter.
> > > > [1] https://elixir.bootlin.com/linux/v6.19-rc5/source/drivers/regulator/core.c#L1227
> > > > [2] https://lkml.iu.edu/2412.3/00826.html
> > >
> > > What's the status of such patches?
> >
> > the patch is ready for review. It's seems like nobody is interested
> I'm sorry to see that the patch had it's first anniversary.
> I'll need to bring out my logic analyzer and test your patch (I hope
> it's precise enough to show the impact of your changes).
> Are your plans then to re-send the patches or have you moved on and
> need someone else to take care of it?

It's a major step anyway if you confirm the issue yourself with an 
analyzer. In that case discussion won't be delayed for one more year
I think. Thanks.

Sure I'm ready to discuss/fix/resend this patch.

--
Best regards
George