linux-kernel - Re: [PATCH v2 00/20] rtc: omap: fixes and power-off feature

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Message-ID: <20141028131257.GS2006@localhost>
Date:	Tue, 28 Oct 2014 14:12:57 +0100
From:	Johan Hovold <johan@...nel.org>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Johan Hovold <johan@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Felipe Balbi <balbi@...com>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Tony Lindgren <tony@...mide.com>,
	Benoît Cousson <bcousson@...libre.com>,
	Lokesh Vutla <lokeshvutla@...com>,
	Guenter Roeck <linux@...ck-us.net>, nsekhar@...com,
	t-kristo@...com, j-keerthy@...com, linux-omap@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
	rtc-linux@...glegroups.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 00/20] rtc: omap: fixes and power-off feature

On Tue, Oct 28, 2014 at 08:47:46AM +0000, Russell King - ARM Linux wrote:
> On Tue, Oct 28, 2014 at 09:16:16AM +0100, Johan Hovold wrote:
> > It looks like we're soon to be having power-off call chains, with
> > configurable priorities, to shut of various parts of the hardware
> 
> I really hope that they *don't* get used like that.  I guess this is
> what happens when people don't read the code before they decide to
> implement something.
> 
> All the reboot/power off/halt methods already call into the driver model,
> and the driver model then iterates over all bound drivers calling their
> "shutdown" method.  So, today, as it has been for years, all device
> drivers are notified of system power off.
> 
> That's where most device drivers should be cleanly stopping their
> hardware.
> 
> The only thing which is left is the actual hardware triggering of the
> action, and that should be what's done via the notifier.

That's not what I was trying to refer to. But the patch set explicitly
allows for multiple, prioritised power-off handlers, which can power
off a board in different ways and with various degrees of success.
Specifically, it allows for fallback handlers in case one or more
power-off handlers fail.

So if we allow for that, what is to prevent the final power-off handler
from failing? And should this not be logged by arch code in the same way
as failure to restart is?

Johan
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