Re: radeon: RFC speed cap detection on ppc64
From: Bjorn Helgaas
Date: Mon Oct 22 2012 - 13:00:00 EST
On Mon, Oct 22, 2012 at 9:44 AM, Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote:
>> That (walking all parent nodes) is probably the safest thing to do. I'm
>> not sure whether it's optimal. It would likely depend on whether you
>> can meaningfully have a bridge that's faster on the downstream side than
>> on the upstream.
> This is architecture goo at heart - would this be better as a helper in
> the PCI and arch PCI code ?
POWER is not the only architecture where host bridges do not appear as
devices in PCI config space -- ia64 has that, too. So the comment is
The link is a point-to-point thing, so this should be a local
negotiation between the radeon device and the upstream bridge. I
don't see the point of walking any farther up the chain.
drm_pcie_get_speed_cap_mask() should also be changed to use
pcie_capability_read_dword() to avoid any issues with v1/v2 PCI
Express Capability structures.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/