From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: [PATCH] - race-free suspend. Was: Re: [linux-pm] [PATCH 0/8] Suspend block api (version 8) Date: Wed, 2 Jun 2010 20:23:00 +1000 Message-ID: <20100602202300.468b73fe@notabene.brown> References: <201006010005.19554.rjw@sisk.pl> <20100601090023.788cabf4@notabene.brown> <201006010232.20263.rjw@sisk.pl> <20100601113309.609349fd@notabene.brown> <20100601122012.1edeaf48@notabene.brown> <20100602153235.340a7852@notabene.brown> <20100602180614.729246ea@notabene.brown> <20100602105039.068c5e00@schatten.dmk.lab> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20100602105039.068c5e00@schatten.dmk.lab> Sender: linux-kernel-owner@vger.kernel.org To: Florian Mickler Cc: Arve =?UTF-8?B?SGrDuG5uZXbDpWc=?= , Thomas Gleixner , "Rafael J. Wysocki" , Alan Stern , Felipe Balbi , Peter Zijlstra , "Paul@smtp1.linux-foundation.org" , LKML , Linux OMAP Mailing List , Linux PM , Alan Cox , James Bottomley List-Id: linux-omap@vger.kernel.org On Wed, 2 Jun 2010 10:50:39 +0200 Florian Mickler wrote: > On Wed, 2 Jun 2010 18:06:14 +1000 > Neil Brown wrote: > > > I cannot imagine why it would take multiple seconds to scan a keypad. > > Can you explain that? > > > > Do you mean while keys are held pressed? Maybe you don't get a wake-up event > > on key-release? In that case your user-space daemon could block suspend > > while there are any pressed keys.... confused. > > IIRC, the device sends interrupts only for first key-down and > last key-up. > To detect simultaneous key-presses you must actively scan it after the > first key-down. That makes sense - thanks. Presumably the first key-press gets to user-space promptly, so the user-space suspend daemon can be told not to suspend until the last key-up. Thanks, NeilBrown