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tty: serial: fsl_lpuart: avoid checking for transfer complete when UARTCTRL_SBK is asserted in lpuart32_tx_empty

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commit 9425914f3d 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: 380c966c09 ("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>
This commit is contained in:
Sherry Sun 2023-03-23 13:44:15 +08:00 • committed by Greg Kroah-Hartman
commit a17bed82c0
1 changed files with 7 additions and 1 deletions
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8
drivers/tty/serial/fsl_lpuart.c
View file

@ -809,11 +809,17 @@ 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;