From: Mark Deneen <mdeneen@xxxxxxxxx> When using RX DMA, the driver won't pass any data to the uart layer until the buffer is flipped. When the port is shutdown, the dma buffers are unmapped, but the head and tail of the ring buffer are not reseted. Since the serial console will keep the port open, this will only present itself when the uart is not shared. To reproduce the issue, with an unpatched driver, run a getty on /dev/ttyS0 with no serial console and exit. Getty will exit, and when the new one returns you will be unable to log in. If you hold down a key long enough to fill the DMA buffer and flip it, you can then log in. Signed-off-by: Mark Deneen <mdeneen@xxxxxxxxx> Acked-by: Leilei Zhao <leilei.zhao@xxxxxxxxx> [nicolas.ferre@xxxxxxxxx: adapt to mainline kernel, handle !DMA case] Cc: <stable@xxxxxxxxxxxxxxx> # v3.12 Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx> --- drivers/tty/serial/atmel_serial.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index 6e68486c83cb..2d925455c1ec 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -1681,6 +1681,12 @@ static void atmel_shutdown(struct uart_port *port) atmel_port->release_tx(port); /* + * Reset ring buffer pointers + */ + atmel_port->rx_ring.head = 0; + atmel_port->rx_ring.tail = 0; + + /* * Free the interrupt */ free_irq(port->irq, port); -- 1.8.2.2 -- 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
