[v2] powerpc/powernv/pci: Work around races in PCI bridge enabling

[Michael Ellerman]

On Fri, 2018-08-17 at 07:30:39 UTC, Benjamin Herrenschmidt wrote:
> The generic code is race when multiple children of a PCI bridge try to
> enable it simultaneously.
> 
> This leads to drivers trying to access a device through a not-yet-enabled
> bridge, and this EEH errors under various circumstances when using parallel
> driver probing.
> 
> There is work going on to fix that properly in the PCI core but it will
> take some time.
> 
> x86 gets away with it because (outside of hotplug), the BIOS enables all
> the bridges at boot time.
> 
> This patch does the same thing on powernv by enabling all bridges that
> have child devices at boot time, thus avoiding subsequent races. It's suitable
> for backporting to stable and distros, while the proper PCI fix will probably
> be significantly more invasive.
> 
> Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
> CC: stable at vger.kernel.org

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/db2173198b9513f7add8009f225afa

cheers