On Fri, 27 Apr 2012 08:23:23 +0200 Christian Melki <christian.melki@xxxxxxxxxxxx> wrote: > Hi. > > I have written a patch for 8250.c that introduces a new ioctl to tell the uart driver to shift disable RTS when uart has been completely emptied. > This idea is to set the ioctl once the master is finished and wants to shift the bus. > We needed this to be in the kernel since we have very little time to shift RTS according to the implemented protocol on top of RS485. > > Is there any interest in the community for such a behavior? We have a set of RS485 ioctls that provide a standard interface for assisting RS485 handling. The interface should probably use those if possible. > The patch is a little ugly right now. It busywaits a maximum amount of time for the shift register to become empty. I don't know how to do it without introducing a latency that is more than our max RTS time shift requirement (50us). I think it could be useful with a generic 8250.c support for this. We've hit the same hardware limit in a couple of other places where you end up having to spin on the last byte. I don't think it's a problem providing it is only triggered when trying to do the RS485 bits with that feature. Alan -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
