Re: [PATCH] PCI/APCI: Move acpi_pci_osc_support() check to negotiation phase

[Rafael J. Wysocki]

On Mon, Jun 7, 2021 at 4:14 PM Joerg Roedel <jroedel@xxxxxxx> wrote:
>
> On Mon, Jun 07, 2021 at 02:56:24PM +0200, Rafael J. Wysocki wrote:
> > On Fri, Jun 4, 2021 at 7:09 PM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
> > >  If either "pcie_ports_disabled" or Linux doesn't support everything in
> > > ACPI_PCIE_REQ_SUPPORT, we will never evaluate _OSC at all, so
> > > the platform won't know that Linux has OSC_PCI_SEGMENT_GROUPS_SUPPORT,
> > > OSC_PCI_HPX_TYPE_3_SUPPORT, OSC_PCI_EXT_CONFIG_SUPPORT, etc.
> >
> > Right.
>
> Thanks Bjorn and Rafael. So I think the important thing to do is to
> issue at least one _OSC call even when Linux is not trying to take
> control of anything.
>
> I look into a clean way to do this and get the kernel messages right.
> One thing to change is probably only calculating 'control' if
> !pcie_ports_disabled in negotiate_os_control().

Please also see
https://lore.kernel.org/linux-acpi/93d783c4-4468-023b-193e-3fc6eca35445@xxxxxxxxxx/
for possible clashes etc.