Hi. On Wednesday 26 April 2006 13:32, David Brownell wrote: > On Tuesday 25 April 2006 6:16 pm, Nigel Cunningham wrote: > > Hi. > > > > On Wednesday 26 April 2006 09:55, David Brownell wrote: > > > On Tuesday 25 April 2006 3:18 pm, Nigel Cunningham wrote: > > > > I saw the 2 suspends, 1 resume comment in another part of the thread, > > > > but don't believe a driver would be able to detect that 2 suspends > > > > and 1 resume call had been made - at least not without some non > > > > volatile ram. > > > > > > The extra suspend is just IMO a symptom of sloppiness, like a "here may > > > be bugs" sign. Not necessarily an issue in its own right. > > > > > > In fact if you count carefully, it's three suspends and one resume: > > > one suspend before calling swsusp_resume, one inside swsusp_resume -- > > > replaced by my patch -- and a correctly matched pair in the kernel > > > being resumed. > > > > That doesn't sound right. Let' see - where's this third one? > > I see your point ... device_suspend() and device_power_down() really > do the same thing, but to different sets of devices. A nastily deceptive > naming convention that I may want to fix someday.
:) > So it's not quite fair counting those separately. Three suspend calls, > sure ... but only two per device. > > > > Also, about non-volatile RAM. Not necessary ... the device hardware > > > holds all the relevant state. The problem is that swsusp is now > > > trashing it with those suspend calls before resuming the real kernel. > > > On the plus side, we already have code being used to resolve the > > > identical issue for kexec(), and all my patch does is to use it. > > > > If devices really do get powered down, then they won't retain the state. > > If they don't actually powerdown, then I see your point. > > While the system is restarting into the snapshot, there's no powerdown. > (Because device_power_down doesn't actually power down devices.) Q.E.D. I thought that at least some devices might go D3cold, or is it always hot? I'm perfectly happy to admit being an ignoramus here - I'm just beginning to work on drivers, so still have a lot to learn. Regards, Nigel -- See our web page for Howtos, FAQs, the Wiki and mailing list info. http://www.suspend2.net IRC: #suspend2 on Freenode
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