linux-kernel - Re: [PATCH v3 3/3] arm: kernel: implement cpuidle

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Message-ID: <20150714204138.GW7557@n2100.arm.linux.org.uk>
Date:	Tue, 14 Jul 2015 21:41:38 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc:	Jisheng Zhang <jszhang@...vell.com>,
	Will Deacon <Will.Deacon@....com>,
	Mark Rutland <Mark.Rutland@....com>,
	"daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"galak@...eaurora.org" <galak@...eaurora.org>,
	"agross@...eaurora.org" <agross@...eaurora.org>,
	"davidb@...eaurora.org" <davidb@...eaurora.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 3/3] arm: kernel: implement cpuidle_ops with psci
 backend

On Tue, Jul 14, 2015 at 03:55:46PM +0100, Lorenzo Pieralisi wrote:
> On Tue, Jul 14, 2015 at 01:29:04PM +0100, Russell King - ARM Linux wrote:
> > On Tue, Jul 14, 2015 at 12:03:02PM +0100, Lorenzo Pieralisi wrote:
> > > On Tue, Jul 14, 2015 at 11:34:21AM +0100, Russell King - ARM Linux wrote:
> > > > > +static struct cpuidle_ops psci_cpuidle_ops __initdata = {
> > > > > +	.suspend = cpu_psci_cpu_suspend,
> > > > > +	.init = cpu_psci_cpu_init_idle,
> > > > > +};
> > > > > +CPUIDLE_METHOD_OF_DECLARE(psci_cpuidle, "psci", &psci_cpuidle_ops);
> > > 
> > > I take this as an ACK to M.Rutland's PSCI code move to drivers/firmware,
> > > right ?
> > 
> > No, that's not something I've particularly looked at.  PSCI doesn't really
> > interest me because I have no systems which (afaik) support it.
> 
> PSCI implementation is currently part of arch/arm which means it is
> used on arch/arm (and related platforms) and you should be interested in it
> for that specific reason.
> 
> It is not about what you are interested on, it is about the code you
> maintain, so please have a look at it, thank you.

I don't maintain it, ARM Ltd does.  ARM Ltd submitted it.  ARM Ltd does
the testing of it.  I'm only someone who passes patches through when
necessary.

"Maintaining" a chunk of code when you have no way to test it is no way
to do maintanence.

If ARM Ltd want me to maintain it, provide me with the tools and knowledge
to do so.

> > > > We don't do this for other stuff - we don't have IRQ_CHIP_OF_DECLARE
> > > > stuff in arch/arm but have the IRQ chip drivers in drivers/irqchip.
> > > > We keep it all togehter in drivers/irqchip, even when the IRQ chip
> > > > driver is only useful on ARM.
> > > 
> > > CPUidle operations are ARM only, they are not used on ARM64, so
> > > they belong in arch/arm (that's the same thing as SMP ops, on ARM64
> > > SMP ops and CPUidle ops are unified through CPU operations).
> > 
> > I don't agree with that.  CPU idle isn't an "ARM thing" at all, it's
> > generic kernel infrastructure.  OF is generic kernel infrastructure too.
> 
> I said "CPUidle operations", not CPUidle, we know CPUidle is not an
> ARM thing.
> 
> > Yet, we're stuffing _all_ the PSCI CPU idle code into
> > drivers/firmware/psci.c, but then stuffing the PSCI OF data structures
> > into arch/arm.  This is utterly _insane_.
> 
> Ok, so we will copy the ARM64 PSCI idle related code to arch/arm
> and we are done with this, or we will have to ifdef drivers/firmware
> code, take your pick.

What the fsck is up with you.  You're talking utter nonsense.

> > There is nothing ARM specific about these CPU idle ops.  They don't
> > belong on arch/arm.
> 
> See above.
> 
> > NAK on this series (and the move of the PSCI code to drivers/firmware)
> 
> I do not accept that. You may NAK this series but you can't object to
> moving PSCI firmware code to drivers/firmware for that reason, so
> please have a look at Mark's patches again and ACK/NAK them for
> a valid reason, it has been a while since he asked.

Sorry, NAK, and end of discussion.  There is nothing more to be said
here.

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