Re: [PATCH for-4.19 2/2] tty/serial: atmel: RS485 HD w/DMA: enable RX after TX is stopped

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Apr 02, 2019 at 12:52:50PM +0300, Razvan Stefanescu wrote:
> commit 69646d7a3689 ("tty/serial: atmel: RS485 HD w/DMA: enable RX after TX is stopped") upstream.
> 
> In half-duplex operation, RX should be started after TX completes.
> 
> If DMA is used, there is a case when the DMA transfer completes but the
> TX FIFO is not emptied, so the RX cannot be restarted just yet.
> 
> Use a boolean variable to store this state and rearm TX interrupt mask
> to be signaled again that the transfer finished. In interrupt transmit
> handler this variable is used to start RX. A warning message is generated
> if RX is activated before TX fifo is cleared.
> 
> Fixes: b389f173aaa1 ("tty/serial: atmel: RS485 half duplex w/DMA: enable
> RX after TX is done")
> Signed-off-by: Razvan Stefanescu <razvan.stefanescu@microchip.com>
> Acked-by: Richard Genoud <richard.genoud@gmail.com>
> Cc: stable <stable@vger.kernel.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  drivers/tty/serial/atmel_serial.c | 24 +++++++++++++++++++++---
>  1 file changed, 21 insertions(+), 3 deletions(-)
> 

Happen to have a version of this for 4.4.y and 4.9.y?

I've queued both of these patches up now, thanks.

greg k-h