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

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Date:   Wed, 31 Jan 2018 13:05:38 +0100
From:   Giulio Benetti <giulio.benetti@...ronovasrl.com>
To:     Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:     Chen-Yu Tsai <wens@...e.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: sunxi-ng: ccu-sun4i-a10: Fix mali changing dclk
 frequency

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.

> 
> Maxime
> 


-- 
Giulio Benetti
R&D Manager &
Advanced Research

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