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Re: PNX8550 Broken on Linux 2.6.24 - Interrupt issues?

To: Daniel Laird <daniel.j.laird@nxp.com>
Subject: Re: PNX8550 Broken on Linux 2.6.24 - Interrupt issues?
From: Ralf Baechle <ralf@linux-mips.org>
Date: Thu, 28 Feb 2008 22:26:38 +0000
Cc: linux-mips@linux-mips.org
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On Thu, Feb 28, 2008 at 12:57:47PM +0000, Daniel Laird wrote:

> I have been happily using Linux 2.6.22.1 for ages on PNX8550 (STB810).
>  I have recently decided to step up and move onto Linux 2.6.24 series.
> However I am not getting very far. :-(
> It seems that all the clock stuff has changed again (since 2.6.22.1)
> and this is causing issues.

Yes, it's a bit special and I don't have any possibility to test the
PNX code so I left it mostly untouched when rewriting the timer code.
Sorry about that but eventually I had to go ahead.  Vitaly Wool
eventually submitted a few patches to fix things but as your testing
seems to show that wasn't quite enough.  That far about the history
of the changes.

> The board crashes as soon as local_irq_enable is called in main.c
> 
> I was wondering if anyone out there might also be running on an
> STB810/JBS PNX8550 based system and have any ideas as to why I am
> crashing.
> I know that PNX8550 does not enable the R4K Clock source stuff as the
> chip is a bit 'special' and requires the two timers to be used instead
> of one.

csrc-r4k.c and cevt-r4k.c assume a standard compliant R4000-style
c0_count and c0_compare register.  The PNX chips violate the expected
behaviour badly so can't use these functions.

But that's not very much of a problem.  The timer code is module and
it is easy to write something like csrc-pnx.c and cevt-pnx.c to drive
a PNX style count/compare timer.

Will look over the code to see if I can spot what crashes the PNXes.

  Ralf

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