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tty: serial: msm_serial: avoid system lockup condition

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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>
This commit is contained in:
Jorge Ramirez-Ortiz 2019-06-10 19:23:08 +02:00 committed by Greg Kroah-Hartman
parent db1b5bc047
commit ba3684f99f
1 changed files with 4 additions and 0 deletions
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4
drivers/tty/serial/msm_serial.c
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@ -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);
}