On Mon, Dec 17, 2001 at 05:55:26PM +0100, [EMAIL PROTECTED] wrote: > > Suspend is quite different from power-cut as devices are still allowed to > > draw up to 0.5mA from the suspended USB (see 9.2.3, USB spec.). While > > being enough for a pm-aware microcontroler to keep its state information > > (like fn-address, device-config, interface alternate setting) in the > > microcontroler registers, it's probably insufficient to keep the firmware > > running or even to have an external ram powered. Hence the device _does_ > > keep its state, but needs to reload firmware (or parts of) on resume. > > > > And the device might simply use an eeprom to save and restore its state > > during suspend/resume. The required state information can be reduced to > > only a few bytes - which are easy to write to some eeprom during the > > 10ms the device may take to complete suspending. > > We cannot assume that the host controller will be powered at all. > In fact at some time we will face suspend to disk which will cut power > altogether. Furthermore the pure usb device state might nopt be enough. > A camera for example may have gamma correction, compression ratio, etc ...
Oh, I assumed we were taking both the STR and STD into consideration ... > While a device might implement a number of nice features, we are bound to > meet a lot which don't. -- Vojtech Pavlik SuSE Labs _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
