PCI problem on MPC8250 target

PCI problem on MPC8250 target

[Conor McLoughlin]

I am trying to debug a problem I have with a custom MPC8250 target
board. This board uses the 8250 host-pci bridge. Off the pci bus
there is a three-port pci-pci bridge. Hanging off one port of this
bridge are a number of DSP chips.

I am using kernel 2.6.8.1. I had been debugging this on 2.4.24 from
ELDK, but 2.6 appears to have resolved some of the problems I
had identified.

The pci bios appears to see both functions of the bridge and three
devices on bus 1.  The problem is in allocating resources for the
devices. I hope that someone here can save me some time and indicate
where I should be looking for the problem.

The hardware is first prototype and therefore no guarantees as to
how it is behaving.
A possible issue is that the bios only sees three out of four
DSPs. The first DSP (device number zero) is not seen. I have
been ignoring this problem for the moment, assuming that this is
some simple issue like device zero being special. We can easily
change the hardware to move this device number if that is the case.

PCI: Probing PCI hardware
PCI: bridge rsrc 0..ffffff (100), parent c0185008
PCI: bridge rsrc 80000000..9fffffff (1200), parent c0185024
PCI: bridge rsrc a0000000..afffffff (200), parent c0185024
PCI: bridge rsrc 0..fff (101), parent c01e6038
PCI: bridge rsrc 0..fffff (200), parent c01e6070
PCI: Cannot allocate resource region 1 of PCI bridge 1
PCI: bridge 1 resource 1 moved to aff00000..afffffff
PCI: bridge rsrc 0..fffff (1201), parent c01e6054
PCI: Cannot allocate resource region 2 of PCI bridge 1
PCI: bridge 1 resource 2 moved to 9ff00000..9fffffff
PCI: bridge rsrc 0..fff (101), parent c01e6038
PCI: reparented PCI Bus #01 [0..fff] under PCI Bus #02
PCI: bridge rsrc 0..fffff (200), parent c01e6070
PCI: Cannot allocate resource region 1 of PCI bridge 2
PCI: bridge 2 resource 1 moved to afe00000..afefffff
PCI: bridge rsrc 0..fffff (1201), parent c01e6054
PCI: Cannot allocate resource region 2 of PCI bridge 2
PCI: bridge 2 resource 2 moved to 9fe00000..9fefffff
PCI:0000:00:00.0: Resource 0: 00000000-0001ffff (f=200)
PCI: Cannot allocate resource region 0 of device 0000:00:00.0
PCI:  parent is c01e6070: a0000000-afffffff (f=200)
PCI:0000:00:00.0: Resource 1: 00000000-01ffffff (f=1208)
PCI: Cannot allocate resource region 1 of device 0000:00:00.0
PCI:  parent is c01e6054: 80000000-9fffffff (f=1200)
PCI:0000:01:01.0: Resource 0: 00000000-003fffff (f=1208)
PCI: Cannot allocate resource region 0 of device 0000:01:01.0
PCI:  parent is c1fd2604: 9ff00000-9fffffff (f=1201)
PCI:0000:01:01.0: Resource 1: 00000000-007fffff (f=200)
PCI: Cannot allocate resource region 1 of device 0000:01:01.0
PCI:  parent is c1fd25e8: aff00000-afffffff (f=200)
PCI:0000:01:01.0: Resource 2: 00000000-0000000f (f=101)
PCI:0000:01:02.0: Resource 0: 00000000-003fffff (f=1208)
PCI: Cannot allocate resource region 0 of device 0000:01:02.0
PCI:  parent is c1fd2604: 9ff00000-9fffffff (f=1201)
PCI:0000:01:02.0: Resource 1: 00000000-007fffff (f=200)
PCI: Cannot allocate resource region 1 of device 0000:01:02.0
PCI:  parent is c1fd25e8: aff00000-afffffff (f=200)
PCI:0000:01:02.0: Resource 2: 00000000-0000000f (f=101)
PCI: Cannot allocate resource region 2 of device 0000:01:02.0
PCI:  parent is c1fd25cc: 00000000-00000fff (f=101)
PCI:0000:01:03.0: Resource 0: 00000000-003fffff (f=1208)
PCI: Cannot allocate resource region 0 of device 0000:01:03.0
PCI:  parent is c1fd2604: 9ff00000-9fffffff (f=1201)
PCI:0000:01:03.0: Resource 1: 00000000-007fffff (f=200)
PCI: Cannot allocate resource region 1 of device 0000:01:03.0
PCI:  parent is c1fd25e8: aff00000-afffffff (f=200)
PCI:0000:01:03.0: Resource 2: 00000000-0000000f (f=101)
PCI: Cannot allocate resource region 2 of device 0000:01:03.0
PCI:  parent is c1fd25cc: 00000000-00000fff (f=101)
PCI: Failed to allocate mem resource #0:400000@a0000000 for 0000:01:01.0
PCI: Failed to allocate mem resource #1:800000@b0000000 for 0000:01:01.0
PCI: Failed to allocate mem resource #0:400000@a0000000 for 0000:01:02.0
PCI: Failed to allocate mem resource #1:800000@b0000000 for 0000:01:02.0
PCI: Failed to allocate I/O resource #2:10@1000 for 0000:01:02.0
PCI: Failed to allocate mem resource #0:400000@a0000000 for 0000:01:03.0
PCI: Failed to allocate mem resource #1:800000@b0000000 for 0000:01:03.0
PCI: Failed to allocate I/O resource #2:10@1000 for 0000:01:03.0


Conor

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Anyone with MPC82xx PCI on kernel 2.6?

[Conor McLoughlin]

I am trying to bring up a custom board which contains an MPC8250, a
three-port PCI-PCI bridge and a few pci devices. I am using kernel
2.6.8.1. I am having a number of problems.

Currently I have just four devices hanging off one secondary bus of the
pci-pci bridge. Apart from the bridge, I have no other devices hanging
off bus 0.  I have nothing yet hanging off bus 2.

                 | bus 0
                 |
     ------------------
     |                |
   ============      ============
   |bridge     |     | bridge    |
   |device 0x10|     |device 0x10|
   |function 0 |     |function 1 |
   ============      ============
       |bus 1             |bus 2
       |                  |
   ---------------------
   |         |         |
  device 1   device 2 device 3

Initially, the bios initialization would not assign resources to my
devices on bus 1. The reason appeared to be that in
pci_read_bridge_bases it reads the memory base and limit registers
from the bridge. As these are initially zero, it sets a limit
of 1MB for the resources assigned to bus 1.
My devices (DSP processors) look for a lot more memory space that that.
I modified the function to assign sufficient resources for my needs
and it now appears to assign memory resources to the devices correctly.

First question: Should the memory limit register be set in the bridge
becore pci_read_bridge_bases? Is it perhaps assumed that the bios (boot
code) sets this up?

I still have an issue with I/O resources that I am ignoring for now.
My primary concern right now is verifying the hardware.

Now I try to access the devices on bus 1. I can read the configuration
space no problem, but get bus error if I read the pci memory space.
Checking everything obvious, I see that the the command register of
the pci-pci bridge does not have the memory or I/O space bits set.
Setting these bits eliminates the bus error.

Second question: What function should set the command register for
the pci-pci bridge to enable access to the secondary bus for
memory and I/O cycles?

Now I am at the stage where I don't get a bus error, but I read all FFs
no matter where I read from bus 1. It doesn't appear to matter if a
device is configured at the address or not.

Next question: What should I look at now?  How do I tell if
the device responded to the pci access?

Any help would be much appreciated.
Conor

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Re: Anyone with MPC82xx PCI on kernel 2.6?

[Conor McLoughlin]

Conor McLoughlin wrote:
> Now I try to access the devices on bus 1. I can read the configuration
> space no problem, but get bus error if I read the pci memory space.
> Checking everything obvious, I see that the the command register of
> the pci-pci bridge does not have the memory or I/O space bits set.
> Setting these bits eliminates the bus error.

I have now discovered that the same bits were not set for the devices
on bus 1. I am now reading reasonable values from the device :-)

I still need to know where these bits should be setup.

Conor

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