linux-kernel - Re: [PATCH v1 35/45] clk: mediatek: Split MT8195 clock drivers and allow module build

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Message-ID: <45f8e284-8d56-898b-0897-94c576e09c2c@collabora.com>
Date:   Wed, 8 Feb 2023 09:59:57 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Chen-Yu Tsai <wenst@...omium.org>
Cc:     mturquette@...libre.com, sboyd@...nel.org, matthias.bgg@...il.com,
        johnson.wang@...iatek.com, miles.chen@...iatek.com,
        chun-jie.chen@...iatek.com, daniel@...rotopia.org,
        fparent@...libre.com, msp@...libre.com, nfraprado@...labora.com,
        rex-bc.chen@...iatek.com, zhaojh329@...il.com,
        sam.shih@...iatek.com, edward-jw.yang@...iatek.com,
        yangyingliang@...wei.com, granquet@...libre.com,
        pablo.sun@...iatek.com, sean.wang@...iatek.com,
        chen.zhong@...iatek.com, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH v1 35/45] clk: mediatek: Split MT8195 clock drivers and
 allow module build

Il 08/02/23 09:28, Chen-Yu Tsai ha scritto:
> On Mon, Feb 6, 2023 at 11:30 PM AngeloGioacchino Del Regno
> <angelogioacchino.delregno@...labora.com> wrote:
>>
>> MT8195 clock drivers were encapsulated in one single (and big) Kconfig
>> option: there's no reason to do that, as it is totally unnecessary to
>> build in all or none of them.
>>
>> Split them out: keep boot-critical clocks as bool and allow choosing
>> non critical clocks as tristate.
> 
> The power domain controller references vppsys*, vdecsys*, vdosys*, wpesys,
> imgsys and camsys. I'd argue that this makes these clock drivers
> semi-boot-critical. Maybe mfgcfg as well when we add the GPU?

You don't need to power on additional power domains if you want to load modules
from a ramdisk! :-)

Besides, you caught me: mtk-pm-domains will be my next target after clocks...
I don't like how it behaves in regard to probe deferrals. Specifically,
I dislike the fact that you either register *all domains* or *none at all*
(unless instantiating two different driver instances and that's ugly).


Angelo

> 
> They should be bundled together at the very least. The power domain
> controller not probing disables all display and multimedia capabilities.
> 
> Also wondering if we should have "default COMMON_CLK_MT8195" ...
> 
> I suppose the same questions apply to other SoCs.
> 
> ChenYu