linux-kernel - Re: [PATCH v3 04/10] pmdomain: mediatek: Refactor bus protection regmaps retrieval

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Message-ID: <be3a2d50-044b-429a-820c-5260c6ce730c@collabora.com>
Date: Tue, 14 Oct 2025 11:59:11 +0200
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Sjoerd Simons <sjoerd@...labora.com>, linux-mediatek@...ts.infradead.org
Cc: robh@...nel.org, conor+dt@...nel.org, mbrugger@...e.com,
 y.oudjana@...tonmail.com, Nícolas F. R. A. Prado
 <nfraprado@...labora.com>, linux-pm@...r.kernel.org, ulf.hansson@...aro.org,
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
 mandyjh.liu@...iatek.com, lihongbo22@...wei.com, wenst@...omium.org,
 matthias.bgg@...il.com, krzk+dt@...nel.org, kernel@...labora.com,
 linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 04/10] pmdomain: mediatek: Refactor bus protection
 regmaps retrieval

Il 13/10/25 15:41, Sjoerd Simons ha scritto:
> Hey,
> 
> On Tue, 2025-08-05 at 09:47 +0200, AngeloGioacchino Del Regno wrote:
>> In preparation to add support for new generation SoCs like MT8196,
>> MT6991 and other variants, which require to set bus protection on
>> different busses than the ones found on legacy chips, and to also
>> simplify and reduce memory footprint of this driver, refactor the
>> mechanism to retrieve and use the bus protection regmaps.
>>
>> This is done by removing the three pointers to struct regmap from
>> struct scpsys_domain (allocated for each power domain) and moving
>> them to the main struct scpsys (allocated per driver instance) as
>> an array of pointers to regmap named **bus_prot.
> 
> Trying to boot v6.18.0-rc1 on a Genio 700 EVK using the arm64 defconfig,
> ends up hanging at boot (seemingly when probing MTU3 and/or mmc, but that
> might be a red herring).
> 
> Either reverting this patch *or* having CONFIG_MTK_MMSYS builtin rather
> then a module seems to solve that.
> 

Thanks for the report.

This is not a problem with this patch specifically, but surely some race condition
that was already present before and that does get uncovered with this one in some
conditions.

Without the devicetree updates (which are not upstream yet) this patch is
fully retaining the legacy functionality 1-to-1.

I'll check what's going on ASAP.

Cheers,
Angelo