linux-kernel - Re: [PATCH v2 2/2] cpufreq: mediatek-hw: Wait for CPU supplies before probing

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Date: Wed, 10 Jan 2024 15:31:27 +0100
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Nícolas F. R. A. Prado <nfraprado@...labora.com>,
 Viresh Kumar <viresh.kumar@...aro.org>,
 "Rafael J . Wysocki" <rafael@...nel.org>,
 Matthias Brugger <matthias.bgg@...il.com>
Cc: kernel@...labora.com, "Hector.Yuan" <hector.yuan@...iatek.com>,
 Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-mediatek@...ts.infradead.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v2 2/2] cpufreq: mediatek-hw: Wait for CPU supplies before
 probing

Il 10/01/24 15:23, Nícolas F. R. A. Prado ha scritto:
> Before proceeding with the probe and enabling frequency scaling for the
> CPUs, make sure that all supplies feeding the CPUs have probed.
> 
> This fixes an issue observed on MT8195-Tomato where if the
> mediatek-cpufreq-hw driver enabled the hardware (by writing to
> REG_FREQ_ENABLE) before the SPMI controller driver (spmi-mtk-pmif),
> behind which lies the big CPU supply, probed the platform would hang
> shortly after with "rcu: INFO: rcu_preempt detected stalls on
> CPUs/tasks" being printed in the log.
> 
> Fixes: 4855e26bcf4d ("cpufreq: mediatek-hw: Add support for CPUFREQ HW")
> Signed-off-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>
> 

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