Hi guys. I've just joined the list in the hope that I might be able to provide some help in getting USB suspend/resume more reliable, or at least get better understanding regarding what the issues are.
On Sun, 2005-01-09 at 05:46, Oliver Neukum wrote: > Am Samstag, 8. Januar 2005 18:52 schrieb Alan Stern: > > > Secondly, the startup kernel gets control of the machine. If the HCD is > > compiled in, then it will grab the HC and reset it. (I would like to know > > how to tell whether that step can be avoided. There's a further > > You can't. You only know after initialisation whether there is an image > to read back. With Suspend2, I could provide a means by which you can check if we're going to resume. As you rightly say, Suspend would need to initialise before it could give an answer, but it should be possible. With the built in swsusp, it's not so simple, but again, it should be possible. > [..] > > If the HCD was build as a module then it may not be loaded at all while > > the startup kernel is running. I forget the details of how this works; > > can the module be loaded from an initrd or equivalent before the image is > > restored? > > IIRC you can't. You can with suspend2. I think swsusp may have had initrd support added recently (there have certainly been patches). > > Thirdly the memory image is restored and the driver in the image is > > running again. Now it may have to take control of the HC from the BIOS, > > from nobody (but after the HC may or may not have been reset), from its > > duplicate in the startup kernel, or from its own former incarnation. And > > it's not so easy to tell which has happened! Fortunately, all it really > > needs to do is another BIOS takeover (if needed) and decide whether a > > reset is required (that's the hard part). Suspend can potentially preserve information from the boot kernel. We should come up with a generic mechanism to do this, though - if it's something that might be helpful in more than one case. Regards, Nigel > > Certainly the current code in the driver doesn't do this correctly. In > > fact, it pretty much ignores the whole issue. Still, I would expect it to > > work in your computer. > > It does, if ehci_hcd isn't loaded. > > Regards > Oliver > > > ------------------------------------------------------- > The SF.Net email is sponsored by: Beat the post-holiday blues > Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. > It's fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt > _______________________________________________ > linux-usb-devel@lists.sourceforge.net > To unsubscribe, use the last form field at: > https://lists.sourceforge.net/lists/listinfo/linux-usb-devel -- Nigel Cunningham Software Engineer, Canberra, Australia http://www.cyclades.com Ph: +61 (2) 6292 8028 Mob: +61 (417) 100 574 ------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It's fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
