[+cc Myron, Amos, Thomas, Ben]
On Mon, Nov 18, 2013 at 2:40 AM, Adam Lee <adam.lee@xxxxxxxxxxxxx> wrote:
> This patch adds the PCI_EXP_FLAGS_SLOT check back before setting
> hotplug bridge, which is omitted by an API switching commit,
> 59875ae489609b2267548dc85160c5f0f0c6f9d4 "PCI/core: Use PCI Express
> Capability accessors".
>
> Some Lenovo laptops hang in booting without this fix.
What kernel version hangs? I suspect you might be missing 6d3a1741f1
("PCI: Support PCIe Capability Slot registers only for ports with
slots"), because it *looks* like the current kernel should work
correctly even without your patch.
If you're missing 6d3a1741f1, I think it's better to fix the hang by
pulling in that patch because it has the potential to fix other bugs
as well. I should have marked that commit for stable, but I didn't
realize at the time that it might fix an actual bug.
This was part of a short series:
1) d3694d4fa3 PCI: Allow PCIe Capability link-related register access
for switches
2) c8b303d020 PCI: Remove PCIe Capability version checks
3) 6d3a1741f1 PCI: Support PCIe Capability Slot registers only for
ports with slots
4) fed2451512 PCI: Remove pcie_cap_has_devctl()
You might also want d3694d4fa3. Without it, we won't read Link
registers for switch ports, which could also cause problems, though I
don't have an example to point at. I'm pretty sure the others (2 and
4) are simplifications only and won't actually fix anything.
Bjorn
> Signed-off-by: Adam Lee <adam.lee@xxxxxxxxxxxxx>
> ---
> drivers/pci/probe.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 5e14f5a..b93d5ac 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -992,8 +992,13 @@ void set_pcie_port_type(struct pci_dev *pdev)
>
> void set_pcie_hotplug_bridge(struct pci_dev *pdev)
> {
> + u16 reg16;
> u32 reg32;
>
> + pcie_capability_read_word(pdev, PCI_EXP_FLAGS, ®16);
> + if (!(reg16 & PCI_EXP_FLAGS_SLOT))
> + return;
> +
> pcie_capability_read_dword(pdev, PCI_EXP_SLTCAP, ®32);
> if (reg32 & PCI_EXP_SLTCAP_HPC)
> pdev->is_hotplug_bridge = 1;
> --
> 1.8.4.3
>
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