[PATCH 5.15 121/148] serial: tegra-tcu: Use uart_xmit_advance(), fixes icount.tx accounting

[Greg Kroah-Hartman]

From: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>

commit 1d10cd4da593bc0196a239dcc54dac24b6b0a74e upstream.

Tx'ing does not correctly account Tx'ed characters into icount.tx.
Using uart_xmit_advance() fixes the problem.

Fixes: 2d908b38d409 ("serial: Add Tegra Combined UART driver")
Cc: <stable@xxxxxxxxxxxxxxx> # serial: Create uart_xmit_advance()
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220901143934.8850-4-ilpo.jarvinen@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/tty/serial/tegra-tcu.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/tty/serial/tegra-tcu.c
+++ b/drivers/tty/serial/tegra-tcu.c
@@ -101,7 +101,7 @@ static void tegra_tcu_uart_start_tx(stru
 			break;
 
 		tegra_tcu_write(tcu, &xmit->buf[xmit->tail], count);
-		xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
+		uart_xmit_advance(port, count);
 	}
 
 	uart_write_wakeup(port);