Re: [PATCH v7] usb:serial:pl2303: add GPIOs interface on PL2303

[Johan Hovold <johan@kernel.org>]

On Thu, Aug 28, 2014 at 07:43:01AM +0800, Wang YanQing wrote:
> On Mon, Aug 18, 2014 at 12:07:20PM +0200, Johan Hovold wrote:
> > On Sun, Aug 17, 2014 at 10:05:36AM +0800, Wang YanQing wrote:
> > > Hi Johan Hovold.
> > > 
> > > Another two questions.
> > > 	
> > > On Tue, Aug 12, 2014 at 04:46:25PM +0200, Johan Hovold wrote:
> > > > 
> > > > > +	int (*gpio_startup)(struct usb_serial *serial);
> > > > > +	void (*gpio_release)(struct usb_serial *serial);
> > > > 
> > > > This isn't the right place for this abstraction. Most of the setup code
> > > > would be common for any device type with GPIOs.
> > > 
> > > I assume you mean any pl2303 variant, not any device type, because
> > > no device in drivers/gpio has common setup code except many of them
> > > use struct gpio_chip.
> > 
> > Yes, pl2303 type/variant. Specifically, much of the setup code will be
> > identical even if say the number of gpio differ (2 or 4) depending on
> > type.
> 
> Yes, indeed unless I know how to make kernel could distinguish those two
> types, this patch willn't be fit for mergence.

It might be possible to do based on the device descriptor (e.g.
bcdDevice). Someone sniffed the official drivers and found some requests
that appeared to be device specific as well.

Unfortunately official documentation from Prolific on this is lacking.

Johan