linux-kernel - Re: [RFC][PATCH -mm 3/3] PM: Disable _request

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Message-ID: <2c0942db0705281351g450bd0c6u31e634757dfa8ac0@mail.gmail.com>
Date:	Mon, 28 May 2007 13:51:15 -0700
From:	"Ray Lee" <ray-lk@...rabbit.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	"Alan Stern" <stern@...land.harvard.edu>,
	"pm list" <linux-pm@...ts.linux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"Matthew Garrett" <mjg59@...f.ucam.org>,
	"Nigel Cunningham" <nigel@...el.suspend2.net>,
	"Pavel Machek" <pavel@....cz>, "Oliver Neukum" <oliver@...kum.org>
Subject: Re: [RFC][PATCH -mm 3/3] PM: Disable _request_firmware before hibernation/suspend

On 5/28/07, Rafael J. Wysocki <rjw@...k.pl> wrote:
> On Monday, 28 May 2007 17:55, Alan Stern wrote:
> > You're using the PM_PRE_FREEZE and PM_POST_THAW notifiers for both this
> > and the userspace helper change.  Is it your intention that drivers
> > should continue to request these services but encounter an error if the
> > request occurs at the wrong time?  Or do you expect drivers to use the
> > notifier chains to know when they shouldn't make any requests?
>
> In fact, I'd like drivers to use notifiers to actually load the firmware into
> memory before hibernation/suspend.  Namely, if there's PM_PRE_FREEZE, the
> driver calls request_firmware() from within the notifier and saves the firmware
> in memory for future use, if need be.  Later, when PM_POST_THAW comes, the
> memory holding the firmware is released.
>
> Unfortunately there are drivers that call request_firmware() directly from
> .resume() which blocks until timeout expires and fails anyway.  I just wanted
> this to fail immediately, without waiting.

Stupid question time. Wouldn't it just be easier to have
request_firmware() keep a copy of the firmware once it's been loaded?
We're not talking about a lot of memory that would be wasted, and that
way no drivers have to be changed.

Ray
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