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

[Giulio Benetti]

Hi,

Il 01/02/2018 13:45, Maxime Ripard ha scritto:
> On Wed, Jan 31, 2018 at 01:05:38PM +0100, Giulio Benetti wrote:
> > Hi,
> >
> > Il 31/01/2018 09:43, Maxime Ripard ha scritto:
> > > Hi,
> > >
> > > On Wed, Jan 31, 2018 at 12:23:59AM +0100, Giulio Benetti wrote:
> > > > When mali.ko is inserted, it set default clocks and call all parent
> > > > clocks to stay into range, causing pll-video0 to change and
> > > > subsequently to change dclk to wrong frequencies.
> > >
> > > This is what you should fix.
> >
> > Ok, so it must be patch title(shrinked of course), right?
> >
> > > > "gpu" clock has lot of parent plls inside driver, but on sun7i
> > > > pll8-gpu does not depend on pll-video0, pll-ve, pll-video1.
> > > >
> > > > It only depends on 24Mhz main clock.
> > >
> > > I don't really know why you are mentionning that. The GPU clock has
> > > all the parents described in the driver. And the parents' parents are
> > > irrelevant to this particular issue.
> > >
> > > > Remove all pll parents from gpu_parents_sun7i except "pll-gpu".
> > >
> > > However, this is not a proper fix for your issue.
> >
> > Yes, you're right, now I understand.
> >
> > It is more complex than I thought.
> > I need to dig more and study better A20 CCU.
> >
> > So this patch can be dropped.
> >
> > > 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.

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)?

> Maxime


--
Giulio Benetti
R&D Manager &
Advanced Research

MICRONOVA SRL
Sede: Via A. Niedda 3 - 35010 Vigonza (PD)
Tel. 049/8931563 - Fax 049/8931346
Cod.Fiscale - P.IVA 02663420285
Capitale Sociale € 26.000 i.v.
Iscritta al Reg. Imprese di Padova N. 02663420285
Numero R.E.A. 258642