Re: [PATCH 33/36] cpuidle,omap3: Use WFI for omap3_pm_idle()

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* Arnd Bergmann [off-list ref] [220608 18:18]:

On Wed, Jun 8, 2022 at 4:27 PM Peter Zijlstra [off-list ref] wrote:

quoted

arch_cpu_idle() is a very simple idle interface and exposes only a
single idle state and is expected to not require RCU and not do any
tracing/instrumentation.

As such, omap_sram_idle() is not a valid implementation. Replace it
with the simple (shallow) omap3_do_wfi() call. Leaving the more
complicated idle states for the cpuidle driver.

Agreed it makes sense to limit deeper idle states to cpuidle. Hopefully
there is some informative splat for attempting to use arch_cpu_ide()
for deeper idle states :)

I see similar code in omap2:

omap2_pm_idle()
 -> omap2_enter_full_retention()
     -> omap2_sram_suspend()

Is that code path safe to use without RCU or does it need a similar change?

Seems like a similar change should be done for omap2. Then anybody who
cares to implement a minimal cpuidle support can do so.

Regards,

Tony