Re: [PATCH 33/36] cpuidle,omap3: Use WFI for omap3_pm_idle()
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- To: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
- Subject: Re: [PATCH 33/36] cpuidle,omap3: Use WFI for omap3_pm_idle()
- From: Arnd Bergmann <arnd@xxxxxxxx>
- Date: Wed, 8 Jun 2022 18:28:33 +0200
- Cc: Richard Henderson <rth@xxxxxxxxxxxxxxx>, Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx>, Matt Turner <mattst88@xxxxxxxxx>, Vineet Gupta <vgupta@xxxxxxxxxx>, Russell King - ARM Linux <linux@xxxxxxxxxxxxxxx>, Hans Ulli Kroll <ulli.kroll@xxxxxxxxxxxxxx>, Linus Walleij <linus.walleij@xxxxxxxxxx>, Shawn Guo <shawnguo@xxxxxxxxxx>, Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>, Sascha Hauer <kernel@xxxxxxxxxxxxxx>, Fabio Estevam <festevam@xxxxxxxxx>, NXP Linux Team <linux-imx@xxxxxxx>, Tony Lindgren <tony@xxxxxxxxxxx>, Kevin Hilman <khilman@xxxxxxxxxx>, Catalin Marinas <catalin.marinas@xxxxxxx>, Will Deacon <will@xxxxxxxxxx>, Guo Ren <guoren@xxxxxxxxxx>, bcain@xxxxxxxxxxx, Huacai Chen <chenhuacai@xxxxxxxxxx>, Xuerui Wang <kernel@xxxxxxxxxx>, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>, Sam Creasey <sammy@xxxxxxxxx>, Michal Simek <monstr@xxxxxxxxx>, Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>, Dinh Nguyen <dinguyen@xxxxxxxxxx>, Jonas Bonn <jonas@xxxxxxxxxxxx>, Stefan Kristiansson <stefan.kristiansson@xxxxxxxxxxxxx>, Stafford Horne <shorne@xxxxxxxxx>, James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>, Helge Deller <deller@xxxxxx>, Michael Ellerman <mpe@xxxxxxxxxxxxxx>, Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>, Paul Mackerras <paulus@xxxxxxxxx>, Paul Walmsley <paul.walmsley@xxxxxxxxxx>, Palmer Dabbelt <palmer@xxxxxxxxxxx>, Albert Ou <aou@xxxxxxxxxxxxxxxxx>, Heiko Carstens <hca@xxxxxxxxxxxxx>, Vasily Gorbik <gor@xxxxxxxxxxxxx>, Alexander Gordeev <agordeev@xxxxxxxxxxxxx>, Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>, Sven Schnelle <svens@xxxxxxxxxxxxx>, Yoshinori Sato <ysato@xxxxxxxxxxxxx>, Rich Felker <dalias@xxxxxxxx>, David Miller <davem@xxxxxxxxxxxxx>, Richard Weinberger <richard@xxxxxx>, Anton Ivanov <anton.ivanov@xxxxxxxxxxxxxxxxxx>, Johannes Berg <johannes@xxxxxxxxxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>, "the arch/x86 maintainers" <x86@xxxxxxxxxx>, "H. 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- In-reply-to: <20220608144518.010587032@infradead.org>
- References: <20220608142723.103523089@infradead.org> <20220608144518.010587032@infradead.org>
On Wed, Jun 8, 2022 at 4:27 PM Peter Zijlstra <peterz@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx>
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
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