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RE: iomemory causing a data bus error

To: Don Hiatt <>, linux-mips <>
Subject: RE: iomemory causing a data bus error
From: Jon Dufresne <>
Date: Thu, 07 Feb 2008 16:01:11 -0500
In-reply-to: <DDFD17CC94A9BD49A82147DDF7D545C57986B1@exchange.ZeugmaSystems.local>
Original-recipient: rfc822;
References: <1202397602.3298.25.camel@localhost> <1202416377.3298.44.camel@localhost> <DDFD17CC94A9BD49A82147DDF7D545C57986B1@exchange.ZeugmaSystems.local>
> Take a look at /proc/interrupts to see if you have something firing
> that you do not expect.

I took a look and this is what I see:

# cat /proc/interrupts 
  2:          0   PNX Level IRQ  GIC
  7:          0   PNX Level IRQ  Timer
 10:        661   PNX Level IRQ  pnx8550-1
 11:        605   PNX Level IRQ  pnx8550-2
 13:          1   PNX Level IRQ  ohci_hcd:usb2
 23:        583   PNX Level IRQ  i2c
 24:        845   PNX Level IRQ  i2c
 28:        334   PNX Level IRQ  pnx8xxx-uart
 34:          1   PNX Level IRQ  Drawing Engine
 47:          0   PNX Level IRQ  vmsp1
 49:          0   PNX Level IRQ  vmsp2
 55:      15876   PNX Level IRQ  libata, ehci_hcd:usb1, ohci_hcd:usb3, 
ohci_hcd:usb4, eth0
 75:         18   PNX Level IRQ  i2c
 78:        192   PNX Level IRQ  i2c
 79:      80239   PNX Level IRQ  timer
 80:         19   PNX Level IRQ  Monotonic timer

ERR:      99373

It looks like there are quite a few devices on irq 55 even before I load
my module. Is it at all possible that I could get my device to use a
different interrupt line? or is this totally restricted by hardware?

Also what does the "ERR" mean? Does this keep a tally of errors? If so
does 99K errors seem high?

> If you are sharing the same IRQ as USB, do you request the IRQ as
> shared? Does the USB as well?

My device does, yes. At this point I have to assume the USB driver is
too. But even if that was the problem, it wouldn't explain why the error
also happens when I don't request the interrupt at all.


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