Re: [PATCH v8] usb:serial:pl2303: add GPIOs interface on PL2303

[Linus Walleij]

On Thu, Sep 4, 2014 at 11:57 PM, Benjamin Henrion <zoobab@xxxxxxxxx> wrote:
> On Thu, Sep 4, 2014 at 7:35 PM, Wang YanQing <udknight@xxxxxxxxx> wrote:
>> On Sun, Aug 31, 2014 at 11:24:56PM +0800, Wang YanQing wrote:
>>> PL2303 USB Serial devices may has GPIOs, this patch add
>>> basic PL2303 gpio support.
>>>
>>> Known issue:
>>> If gpios are in use(export to userspace through sysfs interface, etc),
>>> then call pl2303_release(unplug usb-serial convertor, modprobe -r, etc),
>>> will cause trouble, so we need to make sure there is no gpio user before
>>> call pl2303_release.
>>>
>>> Signed-off-by: Wang YanQing <udknight@xxxxxxxxx>
>>> ---
>>>  Note: I sniffed office HXD gpio test program to get
>>>        gpios control protocol with PL2303 RA, so I only
>>>        test it with PL2303 RA and HXA, I don't have HXD,
>>>        but because it is *office* HXD gpio test program,
>>>        so if it doesn't work with HXD, I will feel surprise.
>
> I can confirm your patch is working fine on the HXD:
>
> http://www.zoobab.com/pl2303hxd-gpio
>
> I am still hunting for a simple C program to test the speed of the
> GPIOs and sysfs, if you have a good reference.

The exercise of the GPIO sysfs interface should be discouraged.
I would put emphasis on in-kernel tests and working on a better
userspace GPIO interface than the sysfs thing.

Yours,
Linus Walleij
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/