Re: Conflict between video-lut and pmu on meson-g12

From: Jiucheng Xu <jiuchengxu@163.com>
To: Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	Marc Gonzalez <marc.w.gonzalez@free.fr>
Cc: AML <linux-amlogic@lists.infradead.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Kevin Hilman <khilman@baylibre.com>,
	Chris Healy <healych@amazon.com>, Will Deacon <will@kernel.org>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Pierre-Hugues Husson <phh@phh.me>,
	jiucheng.xu@amlogic.com
Subject: Re: Conflict between video-lut and pmu on meson-g12
Date: Wed, 1 Mar 2023 15:36:58 +0800	[thread overview]
Message-ID: <a0d7a363-a693-d114-c28a-2290dfa0f89f@163.com> (raw)
In-Reply-To: <CAFBinCBb_5KChqD6wqj_MFxEH_hxL_U3nnA=+1AR8dhdQQVCzw@mail.gmail.com>

+ jiuchengxu@163.com

Amlogic mail sending server has problem. Add my personal email.
Comments inline.

On 2023/3/1 5:49, Martin Blumenstingl wrote:
> [ EXTERNAL EMAIL ]
>
> Hello Jiucheng Xu,
>
> On Tue, Feb 28, 2023 at 10:04 PM Martin Blumenstingl
> <martin.blumenstingl@googlemail.com> wrote:
> [...]
>>> A simple solution might be to specify the "actual" base of
>>> the register set, and count from 0 in the driver?
>> I think your fix is correct (formally it would need to be split into a
>> driver and a .dtsi patch - but let's do things step by step).
> While thinking more about this - I think the whole .dtsi code should
> be improved. Both of the PMU IO regions are part of the &dmc region.
> So I think &pmu should be moved inside &dmc (with the offsets adjusted
> accordingly of course).
Okay I agree with you.I will put &pmu node into &dmc node.
>
> Also I think the dt-bindings are incomplete: according to the driver
> code we're using XTAL as input clock.
> But this is not described anywhere in the dt-bindings.
> dt-bindings should always describe the hardware. The driver can decide
> not to use it but the bindings must always be complete.
Sorry, I couldn't get your point. I didn't know the relationship between
XTAL and DMC. Would you please share more the information?
> And with this comes the question: is the DMC PLL specific to the PMU
> or is it shared with something else (e.g. the actual memory
> controller)? On the 32-bit SoCs (Meson8b/S805 for example) there's a
> whole DDR clock controller (used by the DDR memory controller), so I'm
> wondering if these newer SoCs are still following that approach.
Yes, the PLL is the base input clock of DMC and PMU inside. I have never
seen the meson8b board. I think G12 is a newer generation which has some 
improvement than old
SoCs.

My English is not well. Maybe I doesn't answer your point since I got 
miss-understanding.

Thanks & Best regards
Jiucheng
>
> Best regards,
> Martin
>

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