On Tuesday 30 May 2006 12:17 pm, Pavel Machek wrote: > Hi! > > Looks mostly good... > > > This adds a new pm_message_t event type to use when preparing to switch > > into a swsusp snapshot. Devices that have been initialized by Linux > > after resume (rather than left in power-up-reset state) may need to be > > reset; this new event type gives drivers the chance to do that. > > > > The drivers that will care about this are those which understand more > > hardware states than just "on" and "reset", and read the hardware state > > during resume(). ... > > ...should this go to Documentation/ somewhere? I have a separate doc patch, which I will send once the code passes sufficient muster. > > + * Other transitions are triggered by messages sent using suspend(). All > > + * these transitions quiesce the driver, so that I/O queues are inactive. > > + * That commonly entails turning off IRQs and DMA; there may be rules > > Actually all DMAs must always be turned off. Otherwise swsusp can't > get consistent image. IRQs can be disabled or not (they usually are), however driver > prefers... but DMA must be off. I think there are cases where DMA should still be active, but didn't want to go into them. For FREEZE, DMA should stop, yes. Surely there'd be no point in **disllowing** system states where almost everything is idled (CPU, most peripherals, etc) but the I/O is flowing? Normally it's felt to be a _good_ thing to get the system into modes like that. - Dave
