The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y git checkout FETCH_HEAD git cherry-pick -x 9425914f3de6febbd6250395f56c8279676d9c3c # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023041011-vanilla-unpicked-92cc@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..

Possible dependencies:

9425914f3de6 ("tty: serial: fsl_lpuart: avoid checking for transfer complete when UARTCTRL_SBK is asserted in lpuart32_tx_empty") 46dd6d779dcc ("serial: fsl_lpuart: consider TX FIFO too in lpuart32_tx_empty")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9425914f3de6febbd6250395f56c8279676d9c3c Mon Sep 17 00:00:00 2001 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

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

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index 56e6ba3250cd..edc6e35b701a 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -858,11 +858,17 @@ 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;