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On Thu, Jun 09, 2022 at 10:39:22AM +0300, Tony Lindgren wrote:

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

quoted

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 :)

The arch_cpu_idle() interface doesn't allow one to express a desire for
deeper states. I'm not sure how anyone could even attempt this.

But given what OMAP needs to go deeper, this would involve things that
require RCU, combine that with the follow up patches that rip out all
the trace_.*_rcuidle() hackery from the power and clock domain code,
PROVE_RCU should scream if anybody were to attempt it.