From 483d713ba2f628687058c6f6ce98e508191bdf77 Mon Sep 17 00:00:00 2001 From: Sherry Sun Date: Tue, 1 Aug 2023 10:23:04 +0800 Subject: [PATCH] tty: serial: fsl_lpuart: Clear the error flags by writing 1 for lpuart32 platforms commit 282069845af388b08d622ad192b831dcd0549c62 upstream. Do not read the data register to clear the error flags for lpuart32 platforms, the additional read may cause the receive FIFO underflow since the DMA has already read the data register. Actually all lpuart32 platforms support write 1 to clear those error bits, let's use this method to better clear the error flags. Fixes: 42b68768e51b ("serial: fsl_lpuart: DMA support for 32-bit variant") Cc: stable Signed-off-by: Sherry Sun Link: https://lore.kernel.org/r/20230801022304.24251-1-sherry.sun@nxp.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/fsl_lpuart.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index a4cf00756681..227fb2d32046 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -1062,8 +1062,8 @@ static void lpuart_copy_rx_to_tty(struct lpuart_port *sport) unsigned long sr = lpuart32_read(&sport->port, UARTSTAT); if (sr & (UARTSTAT_PE | UARTSTAT_FE)) { - /* Read DR to clear the error flags */ - lpuart32_read(&sport->port, UARTDATA); + /* Clear the error flags */ + lpuart32_write(&sport->port, sr, UARTSTAT); if (sr & UARTSTAT_PE) sport->port.icount.parity++;