From: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
To: jorge.ramirez-ortiz@linaro.org, agross@kernel.org,
david.brown@linaro.org, gregkh@linuxfoundation.org,
jslaby@suse.com
Cc: linux-arm-msm@vger.kernel.org, linux-serial@vger.kernel.org,
linux-kernel@vger.kernel.org, khasim.mohammed@linaro.org,
bjorn.andersson@linaro.org
Subject: [PATCH] tty: serial: msm_serial: avoid system lockup condition
Date: Mon, 10 Jun 2019 09:37:37 +0200 [thread overview]
Message-ID: <20190610073737.22856-1-jorge.ramirez-ortiz@linaro.org> (raw)
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
reply other threads:[~2019-06-10 7:37 UTC|newest]
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