linux-kernel - Re: [REGRESSION] Suspend to RAM does not work anymore with k3-am62-ti-ipc-firmware.dtsi

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Message-ID: <cf10f312-3ba1-4226-96da-d2c9a149c1c7@ti.com>
Date: Tue, 21 Oct 2025 15:26:17 +0530
From: Beleswar Prasad Padhi <b-padhi@...com>
To: Francesco Dolcini <francesco@...cini.it>
CC: Hiago De Franco <hiagofranco@...il.com>, <nm@...com>, <vigneshr@...com>,
        <kristo@...nel.org>, <robh@...nel.org>, <krzk+dt@...nel.org>,
        <conor+dt@...nel.org>, <afd@...com>, <u-kumar1@...com>,
        <hnagalla@...com>, <jm@...com>, <d-gole@...com>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Robert Nelson <robertcnelson@...il.com>,
        João Paulo Gonçalves <joao.goncalves@...adex.com>,
        Emanuele Ghidoli <emanuele.ghidoli@...adex.com>,
        Francesco Dolcini
	<francesco.dolcini@...adex.com>,
        Matthias Schiffer
	<matthias.schiffer@...tq-group.com>,
        Logan Bristol
	<logan.bristol@...xas.edu>,
        Josua Mayer <josua@...id-run.com>, John Ma
	<jma@...tec.com>,
        Nathan Morrisson <nmorrisson@...tec.com>,
        Garrett Giordano
	<ggiordano@...tec.com>,
        Matt McKee <mmckee@...tec.com>, Wadim Egorov
	<w.egorov@...tec.de>,
        Max Krummenacher <max.krummenacher@...adex.com>,
        Stefan
 Eichenberger <stefan.eichenberger@...adex.com>,
        Hiago De Franco
	<hiago.franco@...adex.com>,
        Diogo Ivo <diogo.ivo@...mens.com>,
        Li Hua Qian
	<huaqian.li@...mens.com>,
        Jan Kiszka <jan.kiszka@...mens.com>,
        Baocheng Su
	<baocheng.su@...mens.com>,
        Benedikt Niedermayr
	<benedikt.niedermayr@...mens.com>,
        <regressions@...ts.linux.dev>
Subject: Re: [REGRESSION] Suspend to RAM does not work anymore with
 k3-am62-ti-ipc-firmware.dtsi


On 21/10/25 15:04, Francesco Dolcini wrote:
> On Tue, Oct 21, 2025 at 02:33:10PM +0530, Beleswar Prasad Padhi wrote:
>> On 20/10/25 19:47, Hiago De Franco wrote:
>>> DM R5 sends a message that is never consumed, since no firmware is
>>> running on the M4 (the core is offline).
>>
>> May I know why you are not running any firmware on the M4
>> rproc? If the intention is just to run the DM R5 core on the SoC,
>> you can disable the IPC by NOT including the
>> "k3-am62-ti-ipc-firmware.dtsi". That was the motivation for the
>> refactoring.
> Verdin AM62 and AM62P are generic SoMs, that can be used for a multitude
> of different use cases. And not having anything running on the M4 is the
> default use case.


If not having anything on M4 is the default use case, it should
be marked as "status=disabled" in the DT.

>
> I think having the node in the DT is the correct way forward, if you
> want to start the M4 firmware you need such a node, so this is enabling
> a valid and useful use case.


Having the node is fine, you can still choose to keep it
disabled by default.

>
>> List of suggestions/solutions in order of preference:
>> 1. If no intention to enable IPC on rprocs:
>>       Do _not_ include k3-am62-ti-ipc-firmware.dtsi
>> 2. If intention is to enable IPC on rprocs:
>>       Make sure rproc firmware is available in rootfs.
>>       rproc would boot up and consume the mbox
>>       msg, suspend would be successful. Tested this
>>       on TI AM62x-sk with commit 1d6161617c, works
>> 3. Add support in mbox driver to flush the pending
>>     queues.
> 2 is not applicable here, and 1 to me is not a good solution.


Why not? Why would you power on the rproc, enable
the mailboxes, carveout some memory if you never
intend to use it?

>  So this
> means that we need #3.
>
>>> #regzbot introduced: 1d6161617c
>> Would not see this as a regression, but rather a new
>> bug for the omap-mailbox driver...
> As a user this is just a regression. It worked fine before, it's not
> working anymore now.


Isn't this partly dependent on the filesystem as well?
You would not see this behavior if you package the
firmware in rootfs, which I assume you did while
testing a49f991e740f

https://lore.kernel.org/all/20250908142826.1828676-17-b-padhi@ti.com/

>
> The fact that the solution might not be in the same file that introduced
> the issue is not a reason for this not being considered a regression.
>
> Francesco
>