Virtualization - Jun 2022 - [PATCH 33/36] cpuidle,omap3: Use WFI for omap3_pm_idle()

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.

Signed-off-by: Peter Zijlstra (Intel) <peterz at infradead.org>
---
 arch/arm/mach-omap2/pm34xx.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -294,7 +294,7 @@ static void omap3_pm_idle(void)
 	if (omap_irq_pending())
 		return;
 
-	omap_sram_idle();
+	omap3_do_wfi();
 }
 
 #ifdef CONFIG_SUSPEND

On Wed, Jun 8, 2022 at 4:27 PM Peter Zijlstra <peterz at infradead.org>
wrote:
>
> 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.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz at infradead.org>
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?

        Arnd