linux-kernel - Re: [PATCH v2 29/47] clk: mediatek: Propagate struct device with mtk_clk_register

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Message-ID: <8a19a7b3-f047-3fc5-5002-ce07c1dbdf4a@collabora.com>
Date:   Fri, 17 Feb 2023 11:57:47 +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, kernel@...labora.com
Subject: Re: [PATCH v2 29/47] clk: mediatek: Propagate struct device with
 mtk_clk_register_dividers()

Il 17/02/23 05:09, Chen-Yu Tsai ha scritto:
> On Tue, Feb 14, 2023 at 9:42 PM AngeloGioacchino Del Regno
> <angelogioacchino.delregno@...labora.com> wrote:
>>
>> Propagate struct device for divider clocks registered through clk-mtk
>> helpers to be able to get runtime PM support for MTK clocks.
> 
> Sidenote: I think we still need to call pm_runtime_enable() (or some other
> function) on the underlying device before any clk_hw_register() calls are
> made for the clk core to pick up runtime PM support?
> 

The clk_core checks...

	if (dev && pm_runtime_enabled(dev))
		core->rpm_enabled = true;

...at __clk_register() time, and there's no way to enable it *later*, which
is something that may or may not be good for us.

We could call pm_runtime_enable() on the clock driver itself (so, in simple_probe)
but that's something I didn't want to do right now because this needs a rather big
amount of testing on multiple SoCs.

But yes I agree with you on that we still need to *flip the switch* to actually
enable rpm support. These commits are meant to make us able to do that in one line,
instead of one line per file :-P

>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> 
> Reviewed-by: Chen-Yu Tsai <wenst@...omium.org>

Thanks! :-)