lkml.org 
[lkml]   [2019]   [Aug]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.4 113/158] tty: serial: msm_serial: avoid system lockup condition
Date
[ Upstream commit ba3684f99f1b25d2a30b6956d02d339d7acb9799 ]

The function msm_wait_for_xmitr can be taken with interrupts
disabled. In order to avoid a potential system lockup - demonstrated
under stress testing conditions on SoC QCS404/5 - make sure we wait
for a bounded amount of time.

Tested on SoC QCS404.

Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/msm_serial.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index 5f0ded6fc4e9..eaeb098b5d6a 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -222,10 +222,14 @@ static void msm_request_rx_dma(struct msm_port *msm_port, resource_size_t base)

static inline void msm_wait_for_xmitr(struct uart_port *port)
{
+ unsigned int timeout = 500000;
+
while (!(msm_read(port, UART_SR) & UART_SR_TX_EMPTY)) {
if (msm_read(port, UART_ISR) & UART_ISR_TX_READY)
break;
udelay(1);
+ if (!timeout--)
+ break;
}
msm_write(port, UART_CR_CMD_RESET_TX_READY, UART_CR);
}
--
2.20.1


\
 
 \ /
  Last update: 2019-08-02 11:39    [W:0.487 / U:0.256 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site