pci issue - wrong detection of pci ressources
j.borkhuis at dutchspace.nl
Sat Apr 19 00:23:16 EST 2008
Christian Ehrhardt wrote:
> I tried to use a radeon r200 based graphic card on a sequoia ppc
> (440epx) board. I wondered about the initialization of radeonfb that
> failed with
> __ioremap(): phys addr 0x0 is RAM lr c029cf80
> radeonfb (0000:00:0a.0): cannot map MMIO
> radeonfb: probe of 0000:00:0a.0 failed with error -5
> I trigger a check in ioremap, because the address it wants to remap is
> 0x0 which can never work. The reason of that is that the pci ressource
> of that graphic card is not properly detected.
> With some help I found two kernels - one that work and one that has
> this issue.
> Unfortunately they are very different:
> good => 220.127.116.11 from the linux-2.6-denx - built for arch=ppc
> bad => we have 2.6.25-rc9 (used in our kvm ppc project atm) - build
> for arch=powerpc
> I tried building the 2.6.25-rc9 with arch=ppc, but that one does not
> boot so far. Because of that I can't surely tell you if it is only
> that difference that breaks the pci detection.
> We need arch=powerpc for our kvm code anyway, so I hope there is
> another solution than to switch to arch=ppc ;-)
I came across a similar problem, which (ultimately) was caused by a lack
of memory reserved for PCI. I moved from 2.6.14(ppc) to 2.6.20(powerpc),
and suddenly some cards stopped working: the BAR registers were not
initialized, so it was not possible to access the cards.
Have a look at the boot-time messages, especially the early messages, as
the PCI subsystem is started very early in the boot process. You could
also try switching on PCI-debugging, and have a look at the debug
messages, or add some extra debugging info to the pci-initialization code.
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