From: Gatien CHEVALLIER <gatien.chevallier@foss.st.com>
To: Marek Vasut <marex@denx.de>, <linux-crypto@vger.kernel.org>
Cc: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Alexandre Torgue" <alexandre.torgue@foss.st.com>,
"Gabriel Fernandez" <gabriel.fernandez@foss.st.com>,
"Herbert Xu" <herbert@gondor.apana.org.au>,
"Maxime Coquelin" <mcoquelin.stm32@gmail.com>,
"Michael Turquette" <mturquette@baylibre.com>,
"Olivia Mackall" <olivia@selenic.com>,
"Rob Herring" <robh@kernel.org>,
"Stephen Boyd" <sboyd@kernel.org>,
"Yang Yingliang" <yangyingliang@huawei.com>,
linux-arm-kernel@lists.infradead.org, linux-clk@vger.kernel.org,
linux-stm32@st-md-mailman.stormreply.com
Subject: Re: [PATCH] [RFC] clk: stm32mp1: Keep RNG1 clock always running
Date: Thu, 16 May 2024 16:35:28 +0200 [thread overview]
Message-ID: <eb3a2581-efc6-40c3-a7ea-551865017d40@foss.st.com> (raw)
In-Reply-To: <2eb2b80e-8650-46cf-9d8f-6dd6a884558a@denx.de>
On 5/16/24 12:43, Marek Vasut wrote:
> On 5/16/24 9:42 AM, Gatien CHEVALLIER wrote:
>
> Hi,
>
>>>>>> What if you add a trace in a random generation function in random.c?
>>>>>
>>>>> Do you have a function name or line number for me ?
>>>>
>>>> I put a trace in _get_random_bytes() in drivers/char/random.c. I'm not
>>>> 100% sure but this should be the entry point when getting a random
>>>> number.
>>>
>>> You're right, there is a read attempt right before the hang, and
>>> __clk_is_enabled() returns 0 in stm32_read_rng() . In fact, it is the
>>> pm_runtime_get_sync() which is returning -EACCES instead of zero, and
>>> this is currently not checked so the failure is not detected before
>>> register access takes place, to register file with clock disabled,
>>> which triggers a hard hang.
>>>
>>> I'll be sending a patch shortly, thanks for this hint !
>>>
>>
>> Great news, indeed the return code isn't checked. Let's use
>> pm_runtime_resume_and_get().
>
> Yes please.
>
> I will wonder why we get EACCES though, that basically means we are
> suspending already. Is it safe to return -errno from rng read function
> in that case ?
The framework expects a function that can return an error code so I
don't see why not. Else the framework would have an issue.
I still haven't figured out what is happening.
Could it be that the kernel is getting entropy with hwrng_fillfn()
like it does periodically to feed the entropy pool and it happens at the
same time as your pm test sequence?
FYI, I have been running your script with (echo devices >
/sys/power/pm_test) for 5 hours now and haven't been able to reproduce
the issue.
>
>>>>>> After this, I'll try to reproduce the issue.
>>>>>
>>>>> If you have a minute to test it on some ST MP15 board, that would
>>>>> be real nice. Thanks !
>>>>
>>>> I tried to reproduce the issue you're facing on a STM32MP157C-DK2 no
>>>> SCMI on the 6.9-rc7 kernel tag. I uses OP-TEE and TF-A in the bootchain
>>>> but this should not have an impact here.
>>>>
>>>> How did you manage to test using "echo core > /sys/power/pm_test"?
>>>> In kernel/power/suspend.c, enter_state(). If the pm_test_level is core,
>>>> then an error is fired with the following trace:
>>>> "Unsupported test mode for suspend to idle, please choose
>>>> none/freezer/devices/platform."
>>>
>>> Could this be firmware related ?
>>>
>>>> I've tried using "echo devices > /sys/power/pm_test" so that I can
>>>> at least test that the driver is put to sleep then wakes up. I do not
>>>> reproduce your issue.
>>>
>>> Can you try 'processors' ?
>>>
>>
>> Given this:
>> #ifdef CONFIG_PM_DEBUG
>> if (pm_test_level != TEST_NONE && pm_test_level <= TEST_CPUS) {
>> pr_warn("Unsupported test mode for suspend to idle
>
> You're supposed to be suspending to 'mem' , not 'idle' . Could that be it ?
Yes you're right, I've been missing that. I do not have "deep" available
in /sys/power/mem_sleep... not upstreamed yet maybe... Have you coded a
PSCI service for this in U-Boot?
I'm either missing something or I can't reproduce your setup.
Thanks,
Gatien
next prev parent reply other threads:[~2024-05-16 14:37 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-13 22:02 [PATCH] [RFC] clk: stm32mp1: Keep RNG1 clock always running Marek Vasut
2024-05-14 8:10 ` Gatien CHEVALLIER
2024-05-14 14:37 ` Marek Vasut
2024-05-15 9:16 ` Gatien CHEVALLIER
2024-05-16 1:06 ` Marek Vasut
2024-05-16 7:42 ` Gatien CHEVALLIER
2024-05-16 10:43 ` Marek Vasut
2024-05-16 14:35 ` Gatien CHEVALLIER [this message]
2024-05-16 20:01 ` Marek Vasut
2024-05-17 15:39 ` Gatien CHEVALLIER
2024-05-21 10:27 ` Marek Vasut
2024-05-28 13:55 ` Gatien CHEVALLIER
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