Re: [PATCH v6 3/5] thermal: renesas: rzg3e: Add thermal driver for the Renesas RZ/G3E SoC

Hi John,


On 05/08/2025 09:49, John Madieu wrote:

[ ... ]

quoted

quoted

I might not get what you are asking, but since I compute the
temperature in the hard IRQ handler, I just wait for it to complete
and notify the completion so I can grab the processed value to notify
the thermal core.

Please let me know if this does not answer your question.

Can you describe how the sensor works ? And perhaps if you have a pointer
to some documentation ?

Here is the documentation [1]. The thermal device is referred to as TSU.

[1] https://www.renesas.com/en/document/mah/rzg3e-group-users-manual-hardware?r=25574493

quoted

   [ ... ]

Thanks for the pointer. I got it now ;)

I'm a bit worried about the latency introduced by this mechanism when 
the system is entering in a thermal pressure episode.

The get_temp function wait for a completion up to 100ms, it is a lot. 
Especially if the userspace can be reading the temperature and blocking 
the read.

There is also the spin_lock taken introducing another lock while the 
get_temp function is holding a mutex on the thermal zone.

Did you it that under stress ?

-- 
<http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs

Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog