Re: autosuspend for hid

On Mon, 21 May 2007, Oliver Neukum wrote:

> > - what to do with devices with force feedback? (or PID devices in 
> >   general). The effect could have up to infinite duration (until it is 
> >   stopped by appropriate "stop" method), and we definitely absolutely 
> >   must not autosuspend a device that is currently in a process of 
> >   playback.
> I suggest we don't suspend them. We'd increment the pm usage count on 
> open and decrement it on close, basically the same we need to do for 
> generic HID devices. I just need a way to identify PID devices.

Hi Oliver,

what about something like

	int hidinput_has_ff(struct hid_device *hid)
	{
	        struct hid_input *hidinput;

	        list_for_each_entry(hidinput, &hid->inputs, list)
			if (test_bit(EV_FF, hidinput->input->evbit))
				return 1;
		return 0;
	}


> > - think again about the output reports queuing. I am now inclined to think 
> >   that we should simply wake the device up once the output report is to be 
> >   delivered to it. There might be different situations other than just 
> >   keyboard LEDs (there can be simply any kind of exotic HID device being 
> >   controlled through hiddev and userspace could want to deliver the output 
> >   report to it immediately, without any queuing)
> If we do "busy style" autosuspend only for devices we positively identify,
> is the point rendered moot? 

Sorry, could you be please more specific? I don't think I understand the 
point here. Thanks.

> > - (and of course coding style)
> It shall be done, but not until the principal features are clear.

Of course.

Thanks,

-- 
Jiri Kosina

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