Re: [PATCH] clk: sunxi-ng: ccu-sun4i-a10: Fix mali changing dclk frequency

[Giulio Benetti]

Il 02/02/2018 11:53, Maxime Ripard ha scritto:
> Hi,
>
> On Thu, Feb 01, 2018 at 05:17:11PM +0100, Giulio Benetti wrote:
> > > > > What kernel version did you use?
> > > >
> > > > Latest mainline.
> > >
> > > I guess this patch could fix it:
> > > http://code.bulix.org/1kitrq-268936?raw
> >
> > This should prevent from modifying parent clock. But my problem was
> > different.
> >
> > On A20, gpu_clk can have different PLL, not I've found out the way
> > to choose right one with assigned-parent-clocks.
> >
> > I have patchset ready for adding A20 mali node, but I need some more
> > time to complete with OPP, then I will submit entire patchset.
> >
> > Now it works correctly, using right pll(dedicated PLL8), setting
> > right frequency.
>
> The point is that we really don't care about which PLL is actually
> being used, as long as the rate is correct and we don't break anything
> else. If the GPU rate is accessible through one of the other PLL, it
> makes even more sense to not use the GPU PLL and keep it disabled,
> since it will result in some power savings.

Ah! I see the point now, very clever system for power saving.
I'm going to check if it's resolutive,
but it sounds good.

> > Btw, do I need to add a board using it, or can I add only Mali node
> > to sun7i-a20.dtsi(plus other little patches)?
>
> You can add it to the DTSI without a board using it (and actually,
> nothing should be in the board DTS, everything in the DT for the Mali
> applies to all boards).

Sure. So I would also add the patch you've addressed me:
http://code.bulix.org/1kitrq-268936?raw
as a commit. Can I submit it in patchset to complete the whole job?

> Maxime


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Giulio Benetti
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Advanced Research

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