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);