From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [linux-pm] [patch/rft 2.6.17-rc2] swsusp resume must not device_suspend() Date: Mon, 24 Apr 2006 23:47:35 +0200 Message-ID: <200604242347.36257.rjw@sisk.pl> References: <200604241429.52022.david-b@pacbell.net> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200604241429.52022.david-b@pacbell.net> Content-Disposition: inline Sender: linux-usb-devel-admin@lists.sourceforge.net Errors-To: linux-usb-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: linux-pm@lists.osdl.org Cc: David Brownell , linux-usb-devel@lists.sourceforge.net, Andrew Morton , Pavel Machek List-Id: linux-pm@vger.kernel.org Hi, On Monday 24 April 2006 23:29, David Brownell wrote: > I've noticed a bunch of problem reports that go like this: > > - boot system with some USB devices attached > - echo disk > /sys/power/state > - ... later resume ... > - now those USB devices don't work right > - unplug them/replug them, all is OK > > I recently observed this myself and tracked down one problem. The solution > involves what kexec() does in much the same situation: before starting a > new kernel, most hardware needs to be reset. Today, swsusp will suspend it > instead, which is the root cause of the problem. > > This seems like something that might need to sit in the MM tree for > a while, as it's a longstanding bug and the fix could shake loose driver > goofs. Luckily there's a partial workaround already in wide use: link > drivers as modules if they use true suspend states (like all USB HCDs), > don't link them statically into the kernel image. > > That workaround is partial because when BIOS takes over a controller, the > resume() method has to handle that nasty case too! Last I checked, all > the USB HCDs do handle that case; and few drivers other than those HCDs > would ever need to worry about such issues. I agree with this change but I think it'll cause some strange things to happen for some time. Greetings, Rafael ------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel