[PATCH] PCI: imx6: fix downstream bus scanning

[Fabio Estevam]

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.