Problem with PCI bus rescan on 460EX
Felix Radensky
felix at embedded-sol.com
Mon Mar 15 17:09:05 EST 2010
Hello Kenji-san,
Kenji Kaneshige wrote:
> Felix Radensky wrote:
>> Hello Kenji-san,
>>
>> Kenji Kaneshige wrote:
>>> I'm not sure, but I guess pci_setup_bridge() didn't update IO
>>> base/limit
>>> and Mem base/limit of the bridge (0000:00:02.0) because of the
>>> following
>>> lines.
>>>
>>> static void pci_setup_bridge(struct pci_bus *bus)
>>> {
>>> struct pci_dev *bridge = bus->self;
>>> struct resource *res;
>>> struct pci_bus_region region;
>>> u32 l, bu, lu, io_upper16;
>>>
>>> if (pci_is_enabled(bridge))
>>> <===============================
>>> return; <===============================
>>>
>>> dev_info(&bridge->dev, "PCI bridge to [bus %02x-%02x]\n",
>>> bus->secondary, bus->subordinate);
>>> ...
>>>
>>> It seems the bridge was already enabled by
>>> pci_assign_unassigned_resources()
>>> at boot time. Does removing those lines make any change?
>>>
>>
>> Yes, with these lines removed bridge memory window is properly
>> allocated.
>
> These lines are to prevent updating IO or memory windows when there are
> some devices working behind the bridge. So please note that removing
> these lines is just for debugging.
>
>
>> For some reason bridge memory is disabled, but if I enable it via
>> setpci, and
>> also enable device memory, then everything works fine. If the system
>> is booted
>> when device behind the bridge is plugged in, bridge memory is enabled.
>>
>
> Maybe because of the following lines, I guess.
>
> void pci_enable_bridges(struct pci_bus *bus)
> {
> struct pci_dev *dev;
> int retval;
>
> list_for_each_entry(dev, &bus->devices, bus_list) {
> if (dev->subordinate) {
> if (!pci_is_enabled(dev)) { <=======
> retval = pci_enable_device(dev);<=======
> pci_set_master(dev); <=======
> }
> ...
>
>
Yes, but removing this check is not enough. The bridge is enabled after
first scan, but it's
memory is disabled. So simply calling pci_enable_device() will not
help, it will return without
enabling memory. I had to call pci_disable_device() before
pci_enable_device() to make things
work.
> One possible cause is that pcibios_enable_device() for the bridge didn't
> return any error even though it didn't work properly (ex. cannot access
> to the command register, and so on) on your platform when there is no
> device behind the bridge. But it is just my guess.
Should pcibios_enable_device() return an error if it fails to enable
bridge memory ?
Thanks.
Felix.
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