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Message-ID: <cc6f98eb-f6b2-4a34-a8ed-c0f759fa4c79@denx.de>
Date: Tue, 14 May 2024 16:37:14 +0200
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Subject: Re: [PATCH] [RFC] clk: stm32mp1: Keep RNG1 clock always running
To: Gatien CHEVALLIER <gatien.chevallier@foss.st.com>,
 linux-crypto@vger.kernel.org
Cc: =?UTF-8?Q?Uwe_Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>,
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 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,
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 <b2d0dfcb-37d6-4375-a4ad-ca96a5339840@foss.st.com>
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From: Marek Vasut <marex@denx.de>
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On 5/14/24 10:10 AM, Gatien CHEVALLIER wrote:
> Hi Marek,

Hi,

> Strange indeed.

Yes.

> A potential reason that comes to my mind would be that something tries 
> to get a random number after the driver suspended and fails to do so.

Possibly.

> Else it might just be a bad clock balance.

I don't think so, this would be reported by the kernel and it would show 
up in /sys/kernel/debug/clk/clk_summary as incrementing use count. It 
would also not happen in a non-deterministic manner like this happens 
here, the hang doesn't always happen after well defined suspend/resume 
cycle count.

> Can you describe the software ecosystem that you're running please?
> (SCMI/no SCMI)?

STM32MP157C DHCOM PDK2 with mainline U-Boot 2024.07-rc2 , no SCMI.

> Do you have the 3 fixes of stm32_rng.c that you've sent recently in your
> software when testing?

Yes, but this happens even without them.

> 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 ?

> 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 !