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| author | Sherry Sun <sherry.sun@nxp.com> | 2023-02-23 17:39:41 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-03-22 13:33:55 +0100 |
| commit | d72ebe4855eb097c370d383e3b2b953f303c6b18 (patch) | |
| tree | b13f56e3e8712e7ca9fec12694eedc93de22df8e /drivers | |
| parent | 4d2304d8f77974209f7dc82f6fc50d94599bf1fe (diff) | |
| download | linux-d72ebe4855eb097c370d383e3b2b953f303c6b18.tar.gz linux-d72ebe4855eb097c370d383e3b2b953f303c6b18.tar.bz2 linux-d72ebe4855eb097c370d383e3b2b953f303c6b18.zip | |
tty: serial: fsl_lpuart: skip waiting for transmission complete when UARTCTRL_SBK is asserted
commit 2411fd94ceaa6e11326e95d6ebf876cbfed28d23 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 skip
waiting for transmission complete when UARTCTRL_SBK is asserted,
otherwise the kernel may stuck here.
And actually set_termios() adds transmission completion waiting to avoid
data loss or data breakage when changing the baud rate, but we don't
need to worry about this when queuing break characters.
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Cc: stable <stable@kernel.org>
Link: https://lore.kernel.org/r/20230223093941.31790-1-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/tty/serial/fsl_lpuart.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index f9d667ce1619..c51883f34ac2 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -2184,9 +2184,15 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios, /* update the per-port timeout */ uart_update_timeout(port, termios->c_cflag, baud); - /* wait transmit engin complete */ - lpuart32_write(&sport->port, 0, UARTMODIR); - lpuart32_wait_bit_set(&sport->port, UARTSTAT, UARTSTAT_TC); + /* + * LPUART Transmission Complete Flag may never be set while queuing a break + * character, so skip waiting for transmission complete when UARTCTRL_SBK is + * asserted. + */ + if (!(old_ctrl & UARTCTRL_SBK)) { + lpuart32_write(&sport->port, 0, UARTMODIR); + lpuart32_wait_bit_set(&sport->port, UARTSTAT, UARTSTAT_TC); + } /* disable transmit and receive */ lpuart32_write(&sport->port, old_ctrl & ~(UARTCTRL_TE | UARTCTRL_RE), |