On Thursday, May 07, 2015 05:54:56 PM One Thousand Gnomes wrote: > On Tue, 05 May 2015 14:31:26 +0200 > > > For example, when you wake up from S3 on ACPI-based systems, the best you > > can get is what devices have generated the wakeup events, but there's > > no input available from that (like you won't know which key has been > > pressed). You may not get that even. You may only know what GPEs have > > caused the wakeup to happen and they may be shared. > > > > For PCI wakeup, the wakeup event may be out of band. You need to walk > > the hierarchy and check the PME status bits to identify the wakeup device > > and then you need to be careful enough not to reset it while putting into > > D0 for the input data associated with the event to be available. I'm not > > sure how many device/driver combinations this actually works for. > > > > For USB wakeup, you get the wakeup event from the controller which may be > > a PCI device. Getting to the USB device itself from there requires some > > work and even then the device may not "remember" what exactly happened. > > > > Further, if you wake up via the PC keyboard from suspend-to-idle, the > > wakeup key code is not available, the only thing you know is that the > > interrupts has occured (that may be changed, but it's how the current > > code works). > > It's probably got to change, otherwise once machines get able to sleep > between keypresses it's going to suck every time you pause and think for > a minute then begin typing. Remember display being off for suspend is > purely a limitation of most current display panels.
Right. It is just one example, though. Take a PCI device in D3hot for another one. It may not even have a buffer to store input data while in that state. The only thing it may be able to do is to signal a PME from it. Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
