* [PATCH] tty: serial: msm_serial: avoid system lockup condition
@ 2019-06-10 7:37 Jorge Ramirez-Ortiz
0 siblings, 0 replies; only message in thread
From: Jorge Ramirez-Ortiz @ 2019-06-10 7:37 UTC (permalink / raw)
To: jorge.ramirez-ortiz, agross, david.brown, gregkh, jslaby
Cc: linux-arm-msm, linux-serial, linux-kernel, khasim.mohammed,
bjorn.andersson
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>
---
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 23833ad952ba..0d4f1fe2b3a2 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -383,10 +383,14 @@ 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);
}
--
2.21.0
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