Re: [PATCH -rt] Buggy uart (for 2.6.16)

[Gunther Mayer]

Steven Rostedt wrote:

> Ingo,
>
> I've noticed that you dropped my "buggy uart" patch.  Probably because
> the 2.6.14 version would cause a deadlock on 2.6.16.  I've sent you a
> new update, but it must have been lost in all the noise.  Here's the
> patch again.  If you don't think this is a bug, try running the attached
> program on the machine that deadlocked (it is the one with the buggy
> uart). Without the patch, the serial_test will miss a wake up, and then
> be stuck in the sleeping TASK_INTERRUPTIBLE state (at least you can
> still kill it).  With the patch, it runs fine.
>
> I ran the program with the following parameters:
>
> # ./serial_test /dev/ttyS0 115200 8 0 0 4
>
> (Disclaimer: I did not write this serial_test.  It was hacked up by my
> customer to show me that this bug exists).
>
> This may also be a bug with the vanilla kernel, since I don't see why it
> is not. I'll run more tests on the vanilla kernel, and if it too misses
> a wake up, I'll submit this to vanilla as well.
>
>
> Some 8250 uarts don't zero out the NO_INTERRUPT bit of the IIR register
>  
Can you name the exact 8250 model which is buggy ?

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