Subject: Fixing PCIe issues on Armada XP

From: [email-masked] (Thomas Petazzoni)
Date: Thu, 10 Apr 2014 23:07:01 +0200

Dear Neil Greatorex,

On Thu, 10 Apr 2014 19:20:37 +0100 (BST), Neil Greatorex wrote:

> I have tested this branch on my Mirabox. I still get the link up problem 
> but if I work around that (see below) the igb driver works flawlessly.
> 
> Tested-by: Neil Greatorex <[email-masked]>

Good, thanks, we're making progress!

> > Remaining issues:
> >
> > * The link up problem. Unfortunately, I tried to reproduce it today,
> >   and didn't manage to. It's weird, because I'm sure I was able to
> >   produce it in the past, but I'm no longer able to, I don't know.
> >   Therefore, it's not easy for me to work on this topic. Neil, Jason,
> >   do you think this is a topic you could potentially handle?
> 
> Do you have earlyprintk enabled? I've found that if I have earlyprintk in 
> my bootargs / command line then I don't get the issue. I assume that is 
> because of timing, but it could be something else?

I have indeed disabled earlyprintk. Initially by removing it from the
command line, and then even by disabling CONFIG_DEBUG_LL.

In fact the original bug report I had came from my colleague Gregory
Clement, who precisely reported to me that a PCIe card was properly
detected on his Armada 385 board when earlyprintk was enabled, but the
PCIe card was not detected when earlyprintk was disabled. At the time,
I was able to reproduce the problem as well on my Armada 385, and
debugged it to find that the mvebu_pcie_set_local_dev_nr().

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com