On uart buffer flush, serial core resets the circular buffer.
If a DMA transfer is in progress at that time, the callback
lpuart_dma_tx_complete will move buffer's tail unconditionally,
hence tail moves beyond head. Use the flush_buffer hook to
terminate the DMA imeaditely and avoid lpuart_dma_tx_complete
being called in this situation.
This bug often showed up while shutdown and lead to duplicate
serial console output.
Signed-off-by: Stefan Agner <stefan@xxxxxxxx>
---
drivers/tty/serial/fsl_lpuart.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index e95c497..7615b5d 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -454,6 +454,15 @@ static int lpuart_dma_rx(struct lpuart_port *sport)
return 0;
}
+static void lpuart_flush_buffer(struct uart_port *port)
+{
+ struct lpuart_port *sport = container_of(port, struct lpuart_port, port);
+ if (sport->lpuart_dma_tx_use) {
+ dmaengine_terminate_all(sport->dma_tx_chan);
+ sport->dma_tx_in_progress = 0;
+ }
+}
+
static void lpuart_dma_rx_complete(void *arg)
{
struct lpuart_port *sport = arg;
@@ -1519,6 +1528,7 @@ static struct uart_ops lpuart_pops = {
.release_port = lpuart_release_port,
.config_port = lpuart_config_port,
.verify_port = lpuart_verify_port,
+ .flush_buffer = lpuart_flush_buffer,
};
static struct uart_ops lpuart32_pops = {
@@ -1537,6 +1547,7 @@ static struct uart_ops lpuart32_pops = {
.release_port = lpuart_release_port,
.config_port = lpuart_config_port,
.verify_port = lpuart_verify_port,
+ .flush_buffer = lpuart_flush_buffer,
};
static struct lpuart_port *lpuart_ports[UART_NR];
--
2.2.2
--
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