On Wed, May 21, 2014 at 05:18:17PM -0600, Bjorn Helgaas wrote:
> ECS is an AMD mechanism that allows access to extended PCI config space
> (offsets 256-4096) via I/O ports CF8/CFCh. We normally use ECAM, i.e.,
> MMCONFIG, to access that space, but apparently old machines have issues
> that meant we couldn't use ECAM.
>
> The solution was to enable ECS so we could use configuration mechanism #1
> (I/O ports CF8/CFCh) to access extended config space. See 831d991821da
> ("x86: add PCI extended config space access for AMD Barcelona").
>
> New machines should be able to use ECAM, which means they don't need the
> CPU-specific code to enable ECS. This patch leaves ECS the same on all
> existing platforms, but stops enabling it on platforms after Fam16h.
>
> Those future platforms should be able to use the standard ACPI MCFG/_CBA
> descriptions of the PCIe ECAM mechanism.
>
> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> CC: Robert Richter <rric@xxxxxxxxxx>
> ---
> arch/x86/pci/amd_bus.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/pci/amd_bus.c b/arch/x86/pci/amd_bus.c
> index aa936e3a2019..67dadf179348 100644
> --- a/arch/x86/pci/amd_bus.c
> +++ b/arch/x86/pci/amd_bus.c
> @@ -405,7 +405,9 @@ static int __init amd_postcore_init(void)
> return 0;
>
> early_fill_mp_bus_info();
> - pci_io_ecs_init();
> +
> + if (boot_cpu_data.x86 <= 0x16)
Fam 0x16, i.e. hex? I think we talked about fam 0x10, i.e. 16 decimal.
Oh well, that's an AMD call now.
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
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