tty/serial: atmel: RS485 half duplex w/DMA: enable RX after TX is done
authorRichard Genoud <richard.genoud@gmail.com>
Tue, 6 Dec 2016 12:05:33 +0000 (13:05 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 11 Jan 2017 07:18:45 +0000 (08:18 +0100)
commitb389f173aaa1204d6dc1f299082a162eb0491545
treed702ef5021258fc6894bec24dcb2e68a06a3c0a5
parent89d8232411a85b9a6b12fd5da4d07d8a138a8e0c
tty/serial: atmel: RS485 half duplex w/DMA: enable RX after TX is done

When using RS485 in half duplex, RX should be enabled when TX is
finished, and stopped when TX starts.

Before commit 0058f0871efe7b01c6 ("tty/serial: atmel: fix RS485 half
duplex with DMA"), RX was not disabled in atmel_start_tx() if the DMA
was used. So, collisions could happened.

But disabling RX in atmel_start_tx() uncovered another bug:
RX was enabled again in the wrong place (in atmel_tx_dma) instead of
being enabled when TX is finished (in atmel_complete_tx_dma), so the
transmission simply stopped.

This bug was not triggered before commit 0058f0871efe7b01c6
("tty/serial: atmel: fix RS485 half duplex with DMA") because RX was
never disabled before.

Moving atmel_start_rx() in atmel_complete_tx_dma() corrects the problem.

Cc: stable@vger.kernel.org
Reported-by: Gil Weber <webergil@gmail.com>
Fixes: 0058f0871efe7b01c6
Tested-by: Gil Weber <webergil@gmail.com>
Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/tty/serial/atmel_serial.c