Re: [PATCH v4 1/3] PCI: pciehp: Add support for async hotplug with native AER and DPC/EDR

[Smita Koralahalli]

On 8/28/2023 12:35 AM, Lukas Wunner wrote:
> On Tue, Aug 15, 2023 at 09:20:41PM +0000, Smita Koralahalli wrote:
> > According to PCIe r6.0 sec 6.7.6 [1], async removal with DPC may result in
> > surprise down error. This error is expected and is just a side-effect of
> > async remove.
> >
> > Add support to handle the surprise down error generated as a side-effect
> > of async remove. Typically, this error is benign as the pciehp handler
> > invoked by PDC or/and DLLSC alongside DPC, de-enumerates and brings down
> > the device appropriately. But the error messages might confuse users. Get
> > rid of these irritating log messages with a 1s delay while pciehp waits
> > for dpc recovery.
> [...]
> > Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@xxxxxxx>
>
> Reviewed-by: Lukas Wunner <lukas@xxxxxxxxx>
>
> The subject is slightly inaccurate as this doesn't touch pciehp source
> files, although it is *related* to pciehp.
>
> As an example, a perhaps more accurate subject might be something like...
>
>    PCI/DPC: Ignore Surprise Down errors on hot removal
>
> ...but I don't think it's necessary to respin just for that as Bjorn is
> probably able to adjust the subject to his liking when applying the patch.
>
> Thanks a lot for patiently pursuing this issue, good to see it fixed.
>
> Five years ago there was an attempt to solve it through masking Surprise
> Down errors, which you've verified to not be a viable approach:
>
> https://patchwork.kernel.org/project/linux-pci/patch/20180818065126.77912-2-okaya@xxxxxxxxxx/
>
> Lukas

Thanks for the review. Would it be possible to consider this patch as a 
standalone while I work on 10-bit tags enumeration? I can do v5 for this 
patch with $SUBJECT changes and also include clearing Atomic Ops and 
10-bit tags unconditionally on hot-remove if that works..

Thanks,
Smita