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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: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -383,10 +383,14 @@ static void msm_request_rx_dma(struct msm_port *msm_port, resource_size_t base)
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static inline void msm_wait_for_xmitr(struct uart_port *port)
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{
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unsigned int timeout = 500000;
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while (!(msm_read(port, UART_SR) & UART_SR_TX_EMPTY)) {
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if (msm_read(port, UART_ISR) & UART_ISR_TX_READY)
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break;
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udelay(1);
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if (!timeout--)
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break;
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}
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msm_write(port, UART_CR_CMD_RESET_TX_READY, UART_CR);
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}
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