[PATCH] [RFC] clk: stm32mp1: Keep RNG1 clock always running

[Marek Vasut]

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 !