Problem with mini-PCI-E slot on P2020RDB

Leon Woestenberg leon.woestenberg at
Fri Apr 8 03:20:24 EST 2011


On Thu, Dec 17, 2009 at 9:28 PM, Felix Radensky <felix at> wrote:
> Kumar Gala wrote:
>> On Dec 17, 2009, at 2:59 AM, Mahajan Vivek-B08308 wrote:
>>>> Thanks a lot. If I understand you correctly, the only way I can get
>>>> ath9k driver to work on this board using legacy interrupts is to wait for a
>>>> hardware fix. Right ?
>>> Correct
>> I'm confused.  What's the issue with IRQ0 on the P2020RDB?  Is it used for
>> another purpose?
> There's a problem with IRQ0 with respect to mini-PCI-E slot. I have Atheros
> wireless card plugged
> into it. ath9k wireless driver for this card uses legacy PCI-E interrupts,
> and I get "irq 16: nobody cared"
> message when driver executes request_irq(). Vivek has come to a conclusion
> that the problem is
> related to incorrect IRQ0 routing for mini-PCI-E slot on P2020RDB.

I would like to understand this issue better, as I seem to be running
into something similar, and it puts my board design on hold.

Can someone (from Freescale) explain what happens if a PCI Express end
point on the mini-PCIe slot raises a legacy interrupt, and where this
goes wrong?

>From what document or source code file can I conclude that the PCIe
legacy interrupt is shared with IRQ0?

I found this:

P1020E/P2020E RDB System Errata, Last Update: 2/15/2010:
Problem:IRQ0 held low
Fix: Add 4.7K pull-up (to 3.3.V) for RTC_INT_N.
See R420 in Rev D schematic.
Add 4.7K pull-up (to 3.3.V) for MCU_INT_N.
See R423 in Rev D schematic.


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