Re: [PATCH 5.10.y-cip 00/22] RZ/{G2L, G2LC, G2UL, G3S, Five, V2L}: Backport MSTOP support

[Pavel Machek <pavel@denx.de>]

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Hi!

> Series backports the MSTOP (Module Stop) support for the Renesas
> RZ/G2L, RZ/G2LC, RZ/G2UL, RZ/G3S, RZ/Five, RZ/V2L SoCs.
> 
> The purpose of MSTOP is to reduce power consumption by stopping
> unnecessary module's functions.
> 
> If any master accesses a module that has the clock stopped and the
> MSTOP bit set, a bus error will occur.
> 
> Due to this, to avoid CPU generating synchronous aborts, changes
> to PM domain specific code were needed. The changes backported in
> this series were adjusted to be executed only for the above
> mentioned Renesas SoCs.
> 
> Please share your thoughts on this approach.

This is a bit more intrusive than I'd like. dev_pm_domain_detach()
changes API and now we have to modify unrelated drivers to fix it up.

How much power does it save? Do we really need this? Could it be done
without changing semantics of existing functions?

>   driver core: platform: Drop dev_pm_domain_detach() call
>   mmc: sdio: Drop dev_pm_domain_detach() call
>   spi: Drop dev_pm_domain_detach() call
>   rpmsg: core: Drop dev_pm_domain_detach() call
>   soundwire: bus: Drop dev_pm_domain_detach() call
>   serdev: Drop dev_pm_domain_detach() call
>   i2c: core: Drop dev_pm_domain_detach() call

Thanks and best regards,

								Pavel
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