From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Date: Sat, 18 Jul 2009 11:49:48 +0000 Subject: Re: [linux-pm] [PATCH 00/04][RFC] PM: Runtime platform device PM Message-Id: <20090718114947.GG1433@ucw.cz> List-Id: References: <20090527100625.29671.43166.sendpatchset@rx1.opensource.se> In-Reply-To: <20090527100625.29671.43166.sendpatchset@rx1.opensource.se> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-sh@vger.kernel.org Hi! > > Sure, conditions may have changed while the system was asleep. They might > > also change while the system is awake. In general, whether or not the system > > was asleep shouldn't make any difference -- to as great an extent as possible > > we should strive to pretend that the entire sleep took no time at all (or > > simply didn't happen). > > > > So: Suppose the system had been awake when the access point > > disappeared. What would the wireless adapter driver do then? It > > should try to do exactly the same thing if the access point disappears > > while the system is asleep. > > Not really. Namely, when the access point _vanishes_ at run time, this is an > error condition from which we have to recover, while if it's _not_ _present_ > after a resume, it's a normal situation and we shouldn't be recovering from > that (the user might have changed the physical location while > suspended). I disagree here. User can just walk away with powered notebook. > > You see? The sleep should be transparent. > > In some cases it won't be, because the hardware state changes while sleeping. > For example, a laptop battery may be depleted while suspended, so that after > resume it's in the 'low' condition, while it was in the 'good' condition before > the preceding suspend. Arguably, you can't drain a battery from 90% to 10%, > for example, momentarily. Also, a CPU fan might be 100% on before > suspend, Actually... going 90%->10% immediately is common behaviour of old li-ion batteries. > because the CPU was hot at that time, but that doesn't mean the fan should be > 100% on after the subsequent resume, because it's likely that the CPU will be > cold (on some systems trying to make the fan spin too fast may lead to > general problems with thermal management afterwards). 100% is indeed sane default for fan. Yes you should slow the fan down when you read the real temperature. And yes some systems play it safe and do 100% fan during boot. (Otherwise you may have heat problems if you suspend and immediately resume). Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html