linux-kernel - Re: [PATCH v4] clk: mediatek: Do a runtime PM get on controllers during probe

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Date: Tue, 12 Mar 2024 15:41:46 +0100
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Pin-yen Lin <treapking@...omium.org>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Matthias Brugger <matthias.bgg@...il.com>
Cc: Chen-Yu Tsai <wenst@...omium.org>, linux-clk@...r.kernel.org,
 linux-kernel@...r.kernel.org, Weiyi Lu <weiyi.lu@...iatek.com>,
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org,
 Bosi Zhang <u201911157@...t.edu.cn>, Nicolas Boichat
 <drinkcat@...omium.org>, Uwe Kleine-König
 <u.kleine-koenig@...gutronix.de>
Subject: Re: [PATCH v4] clk: mediatek: Do a runtime PM get on controllers
 during probe

Il 12/03/24 12:51, Pin-yen Lin ha scritto:
> mt8183-mfgcfg has a mutual dependency with genpd during the probing
> stage, which leads to a deadlock in the following call stack:
> 
> CPU0:  genpd_lock --> clk_prepare_lock
> genpd_power_off_work_fn()
>   genpd_lock()
>   generic_pm_domain::power_off()
>      clk_unprepare()
>        clk_prepare_lock()
> 
> CPU1: clk_prepare_lock --> genpd_lock
> clk_register()
>    __clk_core_init()
>      clk_prepare_lock()
>      clk_pm_runtime_get()
>        genpd_lock()
> 
> Do a runtime PM get at the probe function to make sure clk_register()
> won't acquire the genpd lock. Instead of only modifying mt8183-mfgcfg,
> do this on all mediatek clock controller probings because we don't
> believe this would cause any regression.
> 
> Verified on MT8183 and MT8192 Chromebooks.
> 
> Fixes: acddfc2c261b ("clk: mediatek: Add MT8183 clock support")
> Signed-off-by: Pin-yen Lin <treapking@...omium.org>
> 

MT8195 Cherry Tomato - no issues as well.

Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>