Re: A desktop environment[1] kernel wishlist

Rafael J. Wysocki
2015-05-07T20:38:30Z

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