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tty: serial: fsl_lpuart: terminate DMA on buffer flush 

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@agner.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Stefan Agner 2015-01-26 01:10:16 +01:00 committed by Greg Kroah-Hartman
parent 2fe605df32
commit bfc2e07f91
1 changed files with 11 additions and 0 deletions
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11
drivers/tty/serial/fsl_lpuart.c
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@ -455,6 +455,15 @@ 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;
@ -1496,6 +1505,7 @@ 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 = {
@ -1514,6 +1524,7 @@ 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];