Re: [PATCH 2/2] [RFC] pl2303 autosuspend

Am Donnerstag 25 Oktober 2007 schrieb Sarah Sharp:

> For now, I didn't add a suspend and resume function to the usb_serial_driver
> structure in pl2303.c.  (Hence the need for the first patch to avoid the NULL
> pointer dereference.)  I did add the .supports_autosuspend flag to the
> usb_driver structure with pointers to usb-serial.c's suspend and resume
> functions.  AFAIK, this works with autosuspend in many cases.

It should work for all drivers that don't allocate buffers and URBs
themselves.

> However, I think it will break with kernel swsuspend (and writing "suspend" to
> the level sysfs file) if the tty is open.  I'm looking for suggestions on how to
> make it work, along with any other comments.  I was looking at taking some of
> the code out of the pl2303's close function and putting into a separate kill
> traffic function, but I think it would require some work to be able to be called
> in interrupt context (as I think would be the case with a swsuspend?).

Swsuspend will kill the power session.
You'd need to enable USB_PERSIST and implement reset_resume()

> The other gotcha is that the pl2303 claims to support remote wakeup.  I haven't
> found a good explanation on any datasheet I've seen about *when* remote wakeup
> is triggered.  One datasheet for the pl2303-HX [1] lists a register RW_MODE that
> if set to 0 "When engages remote wakeup, the device issues disconnect signal" or
> if set to 1 "When engages remote wakeup, the device issues resume signal".  If
> anyone can help me decode this, it would be appreciated.

IMHO experimentation will lead to a quicker answer. Enable it and see what happens.

	Regards
		Oliver

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