Re: [RFD] Automatic suspend

Oliver Neukum
2009-03-02T08:24:36Z

Am Sonntag 01 März 2009 23:56:47 schrieb Pavel Machek:
> > Allowing user space to suspend input devices while they are still open
> > is useful. The user-space code that reads from the input devices does
> > not need to know if the device is suspended or not, and the kernel
> > cannot auto suspend input devices based on inactivity.
>
> Actually, I'd like you to fix your userspace and close input devices
> when it does not need them. Given the way you control the platform it
> should not be that hard. I do not see why we'd want to invent new
> interface for "uhuh, I have opened the keyboard but I am not really
> interested in keys being pressed".

Generally you can't do this. A task has an open fd.

- you cannot assume it can open the device again (fd may be inherited)
- keeping the device open makes sure you are talking to the same device
- you may want to avoid repeating expensive initialisations
- some input devices also do output

Regards
Oliver