Hi Lee,

On 12/11/2015 11:01 AM, Lee Armstrong wrote:
> Hi Peter,
> 
> It is on the RX side of things into the BBB and I am seeing the RTS
> signal goign across to our hardware. I think the threshold is 48 out
> of the 64 buffer from looking at and experimenting.
> 
> 3Mbps is the baud rate and yes we were seeing an overrun and then
> corruption of the FIFO. RTS seems to be working now that we have
> worked it out that the throttling happens at 48.> 
> Lee

There are some issues at 3Mbaud, most likely related to dma.
Could be silicon. See here:

https://lkml.org/lkml/2015/12/3/442


> On Fri, Dec 11, 2015 at 6:59 PM Peter Hurley <[email protected] 
> <mailto:[email protected]>> wrote:
> 
>     On 12/11/2015 09:20 AM, Lee Armstrong wrote:
>     > Anyone know what the RTS/CTS thresholds are for the 8250_omap driver
>     > that I am pretty sure the BBB uses by default?
>     >
>     > I can't work it out!  I know that the signalling of RTS is working as
>     > I see it go high on the scope but I need to know how many bytes it is
>     > safe to send before an overrun happens again!
> 
>     The serial core + 8250_omap driver automatically prevent tx fifo
>     overflow; you don't have to worry about overrunning the fifo when
>     writing.
> 
>     Are you observing overruns at the receiver with CRTSCTS on?
>     Is there a message or are you observing data corruption?
>     Is the receiver also a BBB or something else?
>     What baud rate are you using?
> 
>     Regards,
>     Peter Hurley
> 
>     > On Thursday, December 10, 2015 at 7:07:10 PM UTC, Lee Armstrong
>     > wrote:
>     >
>     > Thanks Robert.
>     >
>     > 64 for the FIFO is what I suspected but couldn't see the CTS
>     > threshold. Was that 48?
>     >
>     > Also these look pretty hard coded into the kernel. Anyone know a way
>     > of setting these after a compilation or how to compile in with other
>     > values?
>     >
>     > Lee


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