From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: Re: [PATCH 1/3] PM: Introduce new top level suspend and hibernation callbacks (rev. 8) Date: Mon, 14 Apr 2008 07:05:11 +1000 Message-ID: <1208120711.6958.52.camel@pasglop> References: <200804040111.15255.rjw@sisk.pl> <20080412002302.GA27656@kroah.com> <200804131531.11650.rjw@sisk.pl> <200804131533.03150.rjw@sisk.pl> Reply-To: benh@kernel.crashing.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200804131533.03150.rjw@sisk.pl> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: "Rafael J. Wysocki" Cc: Nigel Cunningham , LKML , Jesse Barnes , ACPI Devel Maling List , pm list , Alexey Starikovskiy , Andrew Morton List-Id: linux-pm@vger.kernel.org On Sun, 2008-04-13 at 15:33 +0200, Rafael J. Wysocki wrote: > + * The PM core executes @prepare() for all devices before starting to > + * execute suspend callbacks for any of them, so drivers may assume all of > + * the other devices to be present and functional while @prepare() is being > + * executed. In particular, it is safe to make GFP_KERNEL memory > + * allocations from within @prepare(). However, drivers may NOT assume > + * anything about the availability of the user space at that time and it > + * is not correct to request firmware from within @prepare() (it's too > + * late to do that). [To work around this limitation, drivers may > + * register suspend and hibernation notifiers that are executed before the > + * freezing of tasks.] Can you tell me why you kept that limitation with user space ? I don't see the point... On the contrary, prepare() is the pefect place to implement handshaking with userspace for drivers that need to do so, such as the DRM. Ben.