pci_enable_device error

[divakar <divakar.chitturi@hpe.com>]

Hi

I am trying to enable the pci device in the driver by calling the 
function, pci_enable_device and i get the below error. 

fpga_pci_uio_driver 0000:4e:00.0: can't enable device: BAR 0 [mem 
0x00000000-0x000fffff 64bit pref] not claimed
fpga_pci_uio_driver 0000:4e:00.0: Failed to enable fpga_pci_uio device 
rc=-22
fpga_pci_uio_driver: probe of 0000:4e:00.0 failed with error -22

I am guessing its coming from pci_enable_resource function in 
pci_setup.c. ( trying to setup debug env to trace exact location)
if (!r->parent) {
                         dev_err(&dev->dev, "can't enable device: BAR %d 
%pR not claimed\n",
                                 i, r);
                         return -EINVAL;
           	}

I am not sure why this condition is false. I am running kernel 3.19 and 
this is a pcie endpoint device sitting on one of the port of the pcie 
switch. Below is the dmesg output for the pcie switch port. 

[   13.586987] pci 0000:4b:04.0: PCI bridge to [bus 4e]
[   13.591069] pci 0000:4b:04.0:   bridge window [mem 0xc7c00000-0xc7ffffff 
64bit pref]

lspci output for my device
lspci -v -s 4e:00.0
4e:00.0 Non-VGA unclassified device:  Company Device 0180 
(rev 01)
        Flags: fast devsel
        Memory at <unassigned> (64-bit, prefetchable) [size=1M]
        Capabilities: [50] MSI: Enable- Count=1/32 Maskable- 64bit+
        Capabilities: [78] Power Management version 3
        Capabilities: [80] Express Endpoint, MSI 00
        Capabilities: [100] Multi-Function Virtual Channel <?>

The other device on different port of the switch work fine. That device 
driver also calls pci_enable_device(dev).

I found a thread http://www.spinics.net/lists/linux-pci/msg49725.html 
discussing something similar. Should i apply any patch to solve it? or 
am i missing something?

Thanks