linux-kernel - Re: [PATCH 2/2] firmware/psci: Set pm_set_resume/suspend_via

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Date: Thu, 28 Dec 2023 10:28:01 +0000
From: Sudeep Holla <sudeep.holla@....com>
To: Konrad Dybcio <konrad.dybcio@...aro.org>
Cc: Mark Rutland <mark.rutland@....com>,
	Sudeep Holla <sudeep.holla@....com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Marijn Suijten <marijn.suijten@...ainline.org>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Bjorn Andersson <andersson@...nel.org>
Subject: Re: [PATCH 2/2] firmware/psci: Set
 pm_set_resume/suspend_via_firmware() on qcom

On Wed, Dec 27, 2023 at 11:15:31PM +0100, Konrad Dybcio wrote:
> Most Qualcomm platforms implementing PSCI (ab)use CPU_SUSPEND for
> entering various stages of suspend, across the SoC. These range from a
> simple WFI to a full-fledged power collapse of the entire chip
> (mostly, anyway).
> 
> Some device drivers are curious to know whether "the firmware" (which is
> often assumed to be ACPI) takes care of suspending or resuming the
> platform. Set the flag that reports this behavior on the aforementioned
> chips.
> 
> Some newer Qualcomm chips ship with firmware that actually advertises
> PSCI SYSTEM_SUSPEND, so the compatible list should only grow slightly.
>

NACK, just use suspend-to-idle if SYSTEM_SUSPEND is not advertised. It is
designed for such platforms especially on x86/ACPI which don't advertise
Sx states. I see no reason why that doesn't work on ARM platforms as well.

-- 
Regards,
Sudeep