[uslcom][patch] Add GPIO support

[JD Louw]

On Sat, Nov 12, 2011 at 9:39 AM, Hans Petter Selasky <hselasky at c2i.net> wrote:
> On Friday 11 November 2011 22:06:19 JD Louw wrote:
>> This patch adds custom IOCTLs to read and write the 4 GPIO pins on the
>> cp2103 usb-to-serial chip. Time from IOCTL to actual pin change is
>> pretty slow though.
>
> Hi,
>
> How slow is it?
>
> Have you tried reducing the interval of the intervalled control request and
> see if there are any changes? Maybe the intervalled control request should be
> started from a timer/callout instead.
>
> --HPS
>

Testing with my running lights app I would guess about 150ms. Reducing
the control interval to 100ms does cause a corresponding IOCTL time
drop. It won't be usable for bit banging, but that's probably not what
the GPIOs were intended for. For my purposes 150 ms is fine.

Is there an example of starting control requests from a timer/callout?
If you want I can have a look, but as it stands I'm happy with it.