Hi! > [ Upstream commit ba3684f99f1b25d2a30b6956d02d339d7acb9799 ] > > 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.
How long did it take to timeout?
Because... this is supposed to loop for 0.5 second with interrupts
disabled, but 500000*udelay(1) is probably going to wait for more than
that.
Is 500msec reasonable with interrupts disabled?
Should it use something like 5000*udelay(100), instead, as that has
chance to result in closer-to-500msec wait?
> +++ 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);
> }
Plus, should it do some kind of dev_err() to let users know that
something went very wrong with their serial?
Thanks,
Pavel
--
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http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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