Re: [PATCH] pps: Make pps_gen_parport depend on BROKEN

[john stultz]

On Fri, 2011-02-18 at 22:16 +0100, Thomas Gleixner wrote:
> This driver causes hard lockups, when the active clock soure is
> jiffies. The reason is that it loops with interrupts disabled waiting
> for a timestamp to be reached by polling getnstimeofday(). Though with
> a jiffies clocksource, when that code runs on the same CPU which is
> responsible for updating jiffies, then we loop in circles for ever
> simply because the timer interrupt cannot update jiffies. So both UP
> and SMP can be affected.

Yuck.

Alexander, Rodolfo: Instead of polling on gtod, could you take a
timestamp, calculate the delay and then use udelay()?

thanks
-john


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