On Jul 20, 2012, at 2:17 AM, Joakim Tjernlund wrote:
>
> Hi Guys
>
> I see that you have been hacking Freescale PCI before so I send this to
> you(and the list)
>
> We are using PCIe(as RC) on P2010(basically a mpc85xx) and have PCI device
> that
> started from user space (needs advance clock conf) so when linux boots there
> is
> no device at all.
> Trying to "hotplug" the device after it is enabled fails, no amount of
> recan/remove using
> either fake or real hotplug makes a difference.
>
> I found the cause eventually but I can't fix it properly as I known almost
> nothing about PCI.
> Cause:
> indirect_pci.c:indirect_read_config() tests for if (hose->indirect_type &
> PPC_INDIRECT_TYPE_NO_PCIE_LINK)
> and returns PCIBIOS_DEVICE_NOT_FOUND
>
> PPC_INDIRECT_TYPE_NO_PCIE_LINK get set by fsl_pci.c (look for
> fsl_pcie_check_link) but is never cleared.
> Clearing it as appropriate makes a small difference. If you
> remove the RC and do a few of rescan's then the device appears.
>
> Hacking some more, like so:
>
> int fsl_pcie_check_link(struct pci_controller *hose)
> {
> u32 val;
>
> early_read_config_dword(hose, 0, 0, PCIE_LTSSM, &val);
> hose->indirect_type |= PPC_INDIRECT_TYPE_NO_PCIE_LINK;
> if (val < PCIE_LTSSM_L0)
> return 1;
> hose->indirect_type &= ~PPC_INDIRECT_TYPE_NO_PCIE_LINK;
> return 0;
> }
> and then using it carefully(it is easy to make linux hang) in
> indirect_read_config():
> indirect_read_config(struct pci_bus *bus, unsigned int devfn, int offset,
> int len, u32 *val)
> {
> struct pci_controller *hose = pci_bus_to_host(bus);
> volatile void __iomem *cfg_data;
> u8 cfg_type = 0;
> u32 bus_no, reg;
>
> if (hose->indirect_type & PPC_INDIRECT_TYPE_NO_PCIE_LINK) {
> if (bus->number != hose->first_busno ||
> devfn != 0) {
> fsl_pcie_check_link(hose);
> return PCIBIOS_DEVICE_NOT_FOUND;
> }
> }
>
> Now it works, just one rescan and the device appears!
> This is a hack, I don't known what other trouble it can cause, I hope you can
> sort this out.
How are you forcing the re-scan? We can see if we can add a re-check of the
link state in that flow somewhere.
Can you do a dump_stack() or something to get a call chain?
- k
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