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