On Thu, Jan 17, 2019 at 05:09:44PM +0100, Johan Hovold wrote: > On Tue, Jan 15, 2019 at 03:46:28PM -0800, Matthias Kaehlcke wrote: > > > Using RTS seems|ed like a nice solutions, since it's the native way to > > prevent the controller from sending data, instead of doing some custom > > hack. However Johan seems to be fairly convinced that flow control and > > manual toggling of RTS can be problematic, and we have seen that > > disabling flow control has its own problems. Maybe it's time to > > consider other solutions like the DISCARD_RX flag we discussed > > earlier. Not that I really liked this custom solution, but in the end > > it might be a more robust way to address the issue. > > > > Johan/Marcel/others: Do you have any further ideas or input on this? > > I don't see why deasserting RTS wouldn't work, well at least as long as > the RTS signal is wired correctly. > > My point was simply that calling serdev_device_set_rts() will generally > not work unless you first disable automatic (i.e. hw-managed) flow > control using serdev_device_set_flow_control(). The exact behaviour is > serial-controller dependent, but I assume the driver needs to be > platform agnostic. I observed that the qcom_geni_serial driver doesn't raise RTS with flow control disabled. It seems we have to investigate why that's the case. I agree that the driver should be platform agnostic. Cheers Matthias
