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tty: serial: linflexuart: Fix magic SysRq handling 

Following an incorrect indentation reported to me by Dan Carpenter, I
noticed that the SysRq lines were inherited from the lpuart driver[1] (note
how the 'continue' is aligned to 'sport->port.sysrq = 0') and we have never
actually tested the SysRq support.

'sport->sysrq = 0' is not necessary neither before nor after 'continue',
because sysrq will already be 0 after uart_handle_sysrq_char() will finish.
Also, since the LINFlexD driver never called uart_handle_break(), sysrq
would have never been set to a nonzero value, so uart_handle_sysrq_char()
was not going to do anything.

Break conditions are detected based on a null data byte along with a
framing error (stop bit sampled to 0).

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/tty/serial/fsl_lpuart.c?h=b3e3bf2ef2c74f5ce5c19510edbbb9bfc1d249c2#n659

Fixes: 09864c1cdf ("tty: serial: Add linflexuart driver for S32V234")
Signed-off-by: Stefan-Gabriel Mirea <stefan-gabriel.mirea@nxp.com>
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20190918184439.7465-1-stefan-gabriel.mirea@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
alistair/sunxi64-5.4-dsi
Stefan-gabriel Mirea 2019-09-18 18:45:49 +00:00 committed by Greg Kroah-Hartman
parent 392fb8df52
commit 9050079719
1 changed files with 14 additions and 7 deletions
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21
drivers/tty/serial/fsl_linflexuart.c
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@ -3,7 +3,7 @@
* Freescale linflexuart serial port driver
*
* Copyright 2012-2016 Freescale Semiconductor, Inc.
* Copyright 2017-2018 NXP
* Copyright 2017-2019 NXP
*/
#if defined(CONFIG_SERIAL_FSL_LINFLEXUART_CONSOLE) && \
@ -246,12 +246,14 @@ static irqreturn_t linflex_rxint(int irq, void *dev_id)
struct tty_port *port = &sport->state->port;
unsigned long flags, status;
unsigned char rx;
bool brk;
spin_lock_irqsave(&sport->lock, flags);
status = readl(sport->membase + UARTSR);
while (status & LINFLEXD_UARTSR_RMB) {
rx = readb(sport->membase + BDRM);
brk = false;
flg = TTY_NORMAL;
sport->icount.rx++;
@ -261,8 +263,11 @@ static irqreturn_t linflex_rxint(int irq, void *dev_id)
status |= LINFLEXD_UARTSR_SZF;
if (status & LINFLEXD_UARTSR_BOF)
status |= LINFLEXD_UARTSR_BOF;
if (status & LINFLEXD_UARTSR_FEF)
if (status & LINFLEXD_UARTSR_FEF) {
if (!rx)
brk = true;
status |= LINFLEXD_UARTSR_FEF;
}
if (status & LINFLEXD_UARTSR_PE)
status |= LINFLEXD_UARTSR_PE;
}
@ -271,13 +276,15 @@ static irqreturn_t linflex_rxint(int irq, void *dev_id)
sport->membase + UARTSR);
status = readl(sport->membase + UARTSR);
if (uart_handle_sysrq_char(sport, (unsigned char)rx))
continue;
if (brk) {
uart_handle_break(sport);
} else {
#ifdef SUPPORT_SYSRQ
sport->sysrq = 0;
if (uart_handle_sysrq_char(sport, (unsigned char)rx))
continue;
#endif
tty_insert_flip_char(port, rx, flg);
tty_insert_flip_char(port, rx, flg);
}
}
spin_unlock_irqrestore(&sport->lock, flags);