From: Sherry Sun <sherry.sun@nxp.com>
Date: Thu, 23 Mar 2023 13:44:15 +0800
Subject: [PATCH] tty: serial: fsl_lpuart: avoid checking for transfer complete
when UARTCTRL_SBK is asserted in lpuart32_tx_empty
References: bsc#1012628
Patch-mainline: 6.2.11
Git-commit: 9425914f3de6febbd6250395f56c8279676d9c3c
commit 9425914f3de6febbd6250395f56c8279676d9c3c upstream.
According to LPUART RM, Transmission Complete Flag becomes 0 if queuing
a break character by writing 1 to CTRL[SBK], so here need to avoid
checking for transmission complete when UARTCTRL_SBK is asserted,
otherwise the lpuart32_tx_empty may never get TIOCSER_TEMT.
Commit 2411fd94ceaa("tty: serial: fsl_lpuart: skip waiting for
transmission complete when UARTCTRL_SBK is asserted") only fix it in
lpuart32_set_termios(), here also fix it in lpuart32_tx_empty().
Fixes: 380c966c093e ("tty: serial: fsl_lpuart: add 32-bit register interface support")
Cc: stable <stable@kernel.org>
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20230323054415.20363-1-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
drivers/tty/serial/fsl_lpuart.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 812216b2..f58f57ad 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -832,11 +832,17 @@ static unsigned int lpuart32_tx_empty(struct uart_port *port)
struct lpuart_port, port);
unsigned long stat = lpuart32_read(port, UARTSTAT);
unsigned long sfifo = lpuart32_read(port, UARTFIFO);
+ unsigned long ctrl = lpuart32_read(port, UARTCTRL);
if (sport->dma_tx_in_progress)
return 0;
- if (stat & UARTSTAT_TC && sfifo & UARTFIFO_TXEMPT)
+ /*
+ * LPUART Transmission Complete Flag may never be set while queuing a break
+ * character, so avoid checking for transmission complete when UARTCTRL_SBK
+ * is asserted.
+ */
+ if ((stat & UARTSTAT_TC && sfifo & UARTFIFO_TXEMPT) || ctrl & UARTCTRL_SBK)
return TIOCSER_TEMT;
return 0;
--
2.35.3