pciehp PCI_BASE_CLASS_DISPLAY check

pciehp PCI_BASE_CLASS_DISPLAY check

[Bjorn Helgaas]

Hi Yinghai,

In 9789ac979b6b ("PCI: pciehp: cleanup flow in
pciehp_configure_device") [1], you added a check that prevents us from
calling pci_configure_slot() for PCI_BASE_CLASS_DISPLAY devices.

Do you remember why we need that check?  I would like to configure
devices in the pci_device_add() path instead of doing it in the
hotplug drivers.  pci_configure_device() is currently called from:

  acpiphp_set_hpp_values()
  pciehp_configure_device()
  shpchp_configure_device()

Only pciehp_configure_device() has the PCI_BASE_CLASS_DISPLAY check.

Bjorn

[1] http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=9789ac979b6b

Re: pciehp PCI_BASE_CLASS_DISPLAY check

[Yinghai Lu]

On Wed, Aug 27, 2014 at 3:03 PM, Bjorn Helgaas <bhelgaas@google.com> wrote:

>
> Only pciehp_configure_device() has the PCI_BASE_CLASS_DISPLAY check.

That commit actually split the loop to two loops, so second loop still
have check.

but later

| Author: Praveen Kalamegham <praveen@nextio.com>
| Date:   Wed May 19 17:03:12 2010 -0500
|
|    PCI: hotplug: pciehp: Removed check for hotplug of display devices
|
|    Removed check to prevent hotplug of display devices within pciehp.
|    Originally this was thought to have been required within the PCI
|    Hotplug specification for some legacy devices.  However there is
|    no such requirement in the most recent revision. The check prevents
|    hotplug of not only display devices but also computational GPUs
|    which require serviceability.

only removed the first one in pciehp_configure_device().

So you can drop that checking.

Thanks

Yinghai

Re: pciehp PCI_BASE_CLASS_DISPLAY check

[Bjorn Helgaas]

On Wed, Aug 27, 2014 at 10:21 PM, Yinghai Lu <yinghai@kernel.org> wrote:
> On Wed, Aug 27, 2014 at 3:03 PM, Bjorn Helgaas <bhelgaas@google.com> wrote:
>
>>
>> Only pciehp_configure_device() has the PCI_BASE_CLASS_DISPLAY check.
>
> That commit actually split the loop to two loops, so second loop still
> have check.
>
> but later
>
> | Author: Praveen Kalamegham <praveen@nextio.com>
> | Date:   Wed May 19 17:03:12 2010 -0500
> |
> |    PCI: hotplug: pciehp: Removed check for hotplug of display devices
> |
> |    Removed check to prevent hotplug of display devices within pciehp.
> |    Originally this was thought to have been required within the PCI
> |    Hotplug specification for some legacy devices.  However there is
> |    no such requirement in the most recent revision. The check prevents
> |    hotplug of not only display devices but also computational GPUs
> |    which require serviceability.
>
> only removed the first one in pciehp_configure_device().
>
> So you can drop that checking.

Great, thanks!  I missed the fact that the check was there before.

Bjorn