linux-kernel - Re: [PATCH v3 21/24] pmdomain: core: Leave powered-on genpds on until late_initcall

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Message-ID: <a29aa004-b4a1-43ce-8dd2-5b05f9999747@nvidia.com>
Date: Thu, 31 Jul 2025 13:53:51 +0100
From: Jon Hunter <jonathanh@...dia.com>
To: Ulf Hansson <ulf.hansson@...aro.org>
Cc: Marek Szyprowski <m.szyprowski@...sung.com>,
 Saravana Kannan <saravanak@...gle.com>, Stephen Boyd <sboyd@...nel.org>,
 linux-pm@...r.kernel.org, "Rafael J . Wysocki" <rafael@...nel.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Michael Grzeschik <m.grzeschik@...gutronix.de>,
 Bjorn Andersson <andersson@...nel.org>, Abel Vesa <abel.vesa@...aro.org>,
 Peng Fan <peng.fan@....nxp.com>,
 Tomi Valkeinen <tomi.valkeinen@...asonboard.com>,
 Johan Hovold <johan@...nel.org>, Maulik Shah <maulik.shah@....qualcomm.com>,
 Michal Simek <michal.simek@....com>, Konrad Dybcio <konradybcio@...nel.org>,
 Thierry Reding <thierry.reding@...il.com>,
 Hiago De Franco <hiago.franco@...adex.com>,
 Geert Uytterhoeven <geert@...ux-m68k.org>,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH v3 21/24] pmdomain: core: Leave powered-on genpds on until
 late_initcall_sync

On 15/07/2025 12:34, Ulf Hansson wrote:

...

>>> Have you found any resolution for this? I have also noticed a boot
>>> regression on one of our Tegra210 boards and bisect is pointing to this
>>> commit. I don't see any particular crash, but a hang on boot.
>>
>> Thanks for reporting!
>>
>> For Exynos we opt-out from the behaviour by enforcing a sync_state of
>> all PM domains upfront [1], which means before any devices get
>> attached.
>>
>> Even if that defeats the purpose of the $subject series, this was one
>> way forward that solved the problem. When the boot-ordering problem
>> (that's how I understood the issue) for Exynos gets resolved, we
>> should be able to drop the hack, at least that's the idea.
>>
>>>
>>> If there is any debug we can enable to see which pmdomain is the problem
>>> let me know.
>>
>> There aren't many debug prints in genpd that I think makes much sense
>> to enable, but you can always give it a try. Since you are hanging,
>> obviously you can't look at the genpd debugfs data...
>>
>> Note that, the interesting PM domains are those that are powered-on
>> when calling pm_genpd_init(). As a start, I would add some debug
>> prints in () to see which PM domains that are relevant to track.
> 
> /s/()/tegra_powergate_add()

I have been able to track this down to a problem in the Tegra PMC driver 
where we are registering the power-domains and I have sent a fix [0]. 
Looks like we have been getting lucky up until now.

Cheers!
Jon

[0] 
https://lore.kernel.org/linux-tegra/20250731121832.213671-1-jonathanh@nvidia.com/T/#u

-- 
nvpublic