Re: [Patch v2] Make PCI extended config space (MMCONFIG) a driver opt-in

Linus Torvalds
2007-12-28T05:38:35Z

On Fri, 28 Dec 2007, Benjamin Herrenschmidt wrote:
>
> I have embedded boards where proper CRS operations is critical since the
> kernel brings the PCIe link up itself, and thus is likely to hit devices
> still in the middle of CRS.

.. but that's perfectly fine. A PCI-E bridge will certainly retry it in
hardware (or it isn't a PCI-E bridge!).

The CRS bit in question is purely the *software*visible* bit - ie whether
the OS gets told about the delay or not. As long as the OS then just
retries the same device, enabling CRS SV is pointless.

So I'm going to disable that thing. If there is some _other_ PCI-E bridge
that is simply buggy, and cannot handle the hw retry itself or is just
otherwise dodgy, we can have a white-list for cases where it really needs
to be done, but the current code is just bogus.

Linus