[PATCH] PCI: imx6: fix downstream bus scanning

[Bjorn Helgaas]

On Tue, May 23, 2017 at 07:11:26PM -0300, Fabio Estevam wrote:
> Hi Bjorn,
> 
> On Mon, May 22, 2017 at 7:13 PM, Bjorn Helgaas <helgaas at kernel.org> wrote:
> 
> > Applied to for-linus for v4.12 with tested-by and acks from Fabio,
> > Peter, and Richard.  I updated the subject line to:
> >
> >   PCI: imx6: Fix config read timeout handling
> >
> > because I don't think this change is specific to bus scanning and I
> > wanted a hint that it's related to the config space mapping changes.
> >
> > In fact, I'd really like to include the specific commit that caused
> > this problem so that if the original commit is backported, there's a
> > hint that we should backport this one, too.  I *think* it might be
> > cc7b0d495589, so I updated the changelog to this:
> >
> >   Commit cc7b0d495589 ("PCI: designware: Update PCI config space remap
> >   function") made PCI configuration requests non-posted, which means we now
> >   get a synchronous abort when the CFG space read to probe for downstream
> >   devices times out.
> >
> >   Synchronous aborts need to be handled differently from the async aborts we
> >   were getting before, in particular the PC needs to be advanced when
> >   resolving the abort.  This is mostly a copy of what other PCI drivers do on
> >   ARM to handle those aborts.
> >
> >   [bhelgaas: changelog, "Fixes"]
> >   Fixes: cc7b0d495589 ("PCI: designware: Update PCI config space remap function")
> >
> > Please let me know if this is the wrong commit.
> 
> I just tested on a mx6q board and can confirm that this is the correct
> offending commit, thanks.

Thanks for checking this out, Fabio!