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From: Sudeep Holla <sudeep.holla@kernel.org>
To: Patrick DELAUNAY <patrick.delaunay@foss.st.com>
Cc: Ulf Hansson <ulfh@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Sudeep Holla <sudeep.holla@kernel.org>,
	Lorenzo Pieralisi <lpieralisi@kernel.org>,
	linux-kernel@vger.kernel.org,
	dario.binacchi@amarulasolutions.com,
	Linux STM32 <linux-stm32@st-md-mailman.stormreply.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [Linux-stm32] [PATCH] firmware: psci: handle unsupported SET_SUSPEND_MODE in PC mode
Date: Thu, 12 Nov 2026 10:13:34 +0000	[thread overview]
Message-ID: <20261112-attentive-gregarious-beagle-9c1fbd@sudeepholla> (raw)
In-Reply-To: <a2432129-613b-4f17-813d-82ac8af9b6d6@foss.st.com>

On Thu, Nov 12, 2026 at 10:40:48AM +0100, Patrick DELAUNAY wrote:
> Hi,
> 
> To complete my previous answer,
> In  last PSCI specification v1.3, we found this description:
> "
> 5.21 PSCI_SET_SUSPEND_MODE
> 5.21.3 Caller responsibilities
> The caller must be able to cope with the following error return codes:
> • NOT_SUPPORTED, in which case the calling OS can assume the platform will
> work in platform-coordinated mode. In this case, the PSCI_FEATURES feature
> flag 0 for CPU_SUSPEND is also 0.
> "
> 

Yes, I can't disagree with that, but ...(see below)

> My patch only implements this behavior:
> the PSCI stack in Linux assumes PC mode when SET_SUSPEND_MODE is not
> supported.
> 

To reiterate my earlier point: if PSCI_FEATURES reports that a function is
unsupported, we shouldn't invoke that FID in the first place. Dealing with an
unexpected NOT_SUPPORTED return from an advertised FID is a separate case, and
we must keep that handling unconditional as it currently stands.

-- 
Regards,
Sudeep

  reply	other threads:[~2026-11-12 10:13 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-29 18:16 Patrick Delaunay
2026-10-30  8:32 ` Sudeep Holla
2026-10-30 10:04   ` Patrick DELAUNAY
2026-11-12  9:40     ` [Linux-stm32] " Patrick DELAUNAY
2026-11-12 10:13       ` Sudeep Holla [this message]
2026-11-12 10:06     ` Sudeep Holla
2026-11-12 10:36       ` Patrick DELAUNAY

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