Re: [RFC PATCH v3 5/5] arm64: Use SYSTEM_OFF2 PSCI call to power off for hibernate

From: David Woodhouse <dwmw2@infradead.org>
To: Marc Zyngier <maz@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org,
	Paolo Bonzini <pbonzini@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Oliver Upton <oliver.upton@linux.dev>,
	James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Lorenzo Pieralisi <lpieralisi@kernel.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>,
	Mostafa Saleh <smostafa@google.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	 linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	kvmarm@lists.linux.dev,  linux-pm@vger.kernel.org
Subject: Re: [RFC PATCH v3 5/5] arm64: Use SYSTEM_OFF2 PSCI call to power off for hibernate
Date: Fri, 22 Mar 2024 16:55:04 +0000	[thread overview]
Message-ID: <12bc0c787fc20e1a3f5dc2588a2712d996ac6d38.camel@infradead.org> (raw)
In-Reply-To: <86edc2z0hs.wl-maz@kernel.org>

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On Fri, 2024-03-22 at 16:37 +0000, Marc Zyngier wrote:
> 
> I agree that nothing really breaks, but I also hold the view that
> broken firmware implementations should be given the finger, specially
> given that you have done this work *ahead* of the spec. I would really
> like this to fail immediately on these and not even try to suspend.
> 
> With that in mind, if doesn't really matter whether HIBERNATE_OFF is
> mandatory or not. We really should check for it and pretend it doesn't
> exist if the correct flag isn't set.

Ack.

I'll rename that variable to 'psci_system_off2_hibernate_supported' then.

static void __init psci_init_system_off2(void)
{
	int ret;

	ret = psci_features(PSCI_FN_NATIVE(1_3, SYSTEM_OFF2));
	if (ret < 0)
		return;

	if (ret & (1 << PSCI_1_3_HIBERNATE_TYPE_OFF))
		psci_system_off2_hibernate_supported = true;
}

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