Commit ba3684f9 authored by Jorge Ramirez-Ortiz's avatar Jorge Ramirez-Ortiz Committed by Greg Kroah-Hartman

tty: serial: msm_serial: avoid system lockup condition

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: default avatarJorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent db1b5bc0
...@@ -383,10 +383,14 @@ static void msm_request_rx_dma(struct msm_port *msm_port, resource_size_t base) ...@@ -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) 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)) { while (!(msm_read(port, UART_SR) & UART_SR_TX_EMPTY)) {
if (msm_read(port, UART_ISR) & UART_ISR_TX_READY) if (msm_read(port, UART_ISR) & UART_ISR_TX_READY)
break; break;
udelay(1); udelay(1);
if (!timeout--)
break;
} }
msm_write(port, UART_CR_CMD_RESET_TX_READY, UART_CR); msm_write(port, UART_CR_CMD_RESET_TX_READY, UART_CR);
} }
......
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