From: Stefan-gabriel Mirea <stefan-gabriel.mirea@nxp.com>
To: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"jslaby@suse.com" <jslaby@suse.com>
Cc: "linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
kbuild test robot <lkp@intel.com>,
Dan Carpenter <dan.carpenter@oracle.com>
Subject: [PATCH] tty: serial: linflexuart: Fix magic SysRq handling
Date: Wed, 18 Sep 2019 18:45:49 +0000 [thread overview]
Message-ID: <20190918184439.7465-1-stefan-gabriel.mirea@nxp.com> (raw)
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: 09864c1cdf5c ("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>
---
drivers/tty/serial/fsl_linflexuart.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/drivers/tty/serial/fsl_linflexuart.c b/drivers/tty/serial/fsl_linflexuart.c
index 68d74f2b5106..a32f0d2afd59 100644
--- a/drivers/tty/serial/fsl_linflexuart.c
+++ b/drivers/tty/serial/fsl_linflexuart.c
@@ -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);
--
2.22.0
reply other threads:[~2019-09-18 18:46 UTC|newest]
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