Yeah I noticed that. I was hoping to go the ioctl route because I'm working 
on a cape that gives the option of RS232 or RS485 on UART4, so the runtime 
switching would be great. 

Hopefully I'm just doing something stupid, but I can't get it to work 
through ioctl. I've tried in both C and Python on an Angstrom image with 
3.8, this testing image, and an old Angstrom with 3.2 on the original BB. 
The tests I'm trying are here: https://gist.github.com/alexanderhiam/8548894

On all three bones the C ioctl() call raise errno 25. On the two with 3.8 
the Python ioctl() call raises 'IOError: [Errno 25] Inappropriate ioctl for 
device' and on the bone with 3.2 it raises 'IOError: [Errno 22] Invalid 
argument'. 

I was under the impression that you had to enable the RS485 ioctl settings 
when building the kernel, but I can't remember where I got that idea and I 
haven't actually tried it yet :p

Perhaps I should start a new thread for this one...

-Alex


On Tuesday, January 21, 2014 3:49:38 PM UTC-5, RobertCNelson wrote:
>
> On Tue, Jan 21, 2014 at 2:33 PM, Robert Nelson 
> <[email protected]<javascript:>> 
> wrote: 
> > On Tue, Jan 21, 2014 at 2:14 PM, Alexander Hiam 
> > <[email protected]<javascript:>> 
> wrote: 
> >> Thanks Robert, I just booted it for the first time and so far so good. 
> I see 
> >> that there's still no ioctl for RS485 mode on the UARTs though. Is 
> there a 
> >> reason RS485 support isn't enabled on the BB kernel builds? 
> > 
> > There is no module for "rs485" you need to call the omap-serial driver 
> > with the proper ioctls 
> > 
> > 
> https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/tree/Documentation/serial/serial-rs485.txt?id=refs/tags/v3.8.13
>  
>
> Looks like you can enable it on boot time too.. 
>
> https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/tree/Documentation/devicetree/bindings/serial/rs485.txt?id=refs/tags/v3.8.13#n28
>  
>
> Regards, 
>
> -- 
> Robert Nelson 
> http://www.rcn-ee.com/ 
>

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