[PATCH v2 2/3] serial: tegra: Use uart_xmit_advance(), fixes icount.tx accounting

[Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>]

DMA complete & stop paths did not correctly account Tx'ed characters
into icount.tx. Using uart_xmit_advance() fixes the problem.

Cc: <stable@xxxxxxxxxxxxxxx> # serial: Create uart_xmit_advance()
Fixes: e9ea096dd225 ("serial: tegra: add serial driver")
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
---
 drivers/tty/serial/serial-tegra.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index ad4f3567ff90..a5748e41483b 100644
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -525,7 +525,7 @@ static void tegra_uart_tx_dma_complete(void *args)
 	count = tup->tx_bytes_requested - state.residue;
 	async_tx_ack(tup->tx_dma_desc);
 	spin_lock_irqsave(&tup->uport.lock, flags);
-	xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
+	uart_xmit_advance(&tup->uport, count);
 	tup->tx_in_progress = 0;
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(&tup->uport);
@@ -613,7 +613,6 @@ static unsigned int tegra_uart_tx_empty(struct uart_port *u)
 static void tegra_uart_stop_tx(struct uart_port *u)
 {
 	struct tegra_uart_port *tup = to_tegra_uport(u);
-	struct circ_buf *xmit = &tup->uport.state->xmit;
 	struct dma_tx_state state;
 	unsigned int count;
 
@@ -624,7 +623,7 @@ static void tegra_uart_stop_tx(struct uart_port *u)
 	dmaengine_tx_status(tup->tx_dma_chan, tup->tx_cookie, &state);
 	count = tup->tx_bytes_requested - state.residue;
 	async_tx_ack(tup->tx_dma_desc);
-	xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
+	uart_xmit_advance(&tup->uport, count);
 	tup->tx_in_progress = 0;
 }
 
-- 
2.30.2