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SubjectRe: [PATCH v2 2/2] PCI: NVMe device specific reset quirk
On Mon, 23 Jul 2018 17:40:02 -0700
Sinan Kaya <okaya@kernel.org> wrote:

> On 7/23/2018 5:13 PM, Alex Williamson wrote:
> > + * The NVMe specification requires that controllers support PCIe FLR, but
> > + * but some Samsung SM961/PM961 controllers fail to recover after FLR (-1
> > + * config space) unless the device is quiesced prior to FLR.
>
> Does disabling the memory bit in PCI config space as part of the FLR
> reset function help? (like the very first thing)

No, it does not. I modified this to only clear PCI_COMMAND_MEMORY and
call pcie_flr(), the Samsung controller dies just as it did previously.

> Can we do that in the pcie_flr() function to cover other endpoint types
> that might be pushing traffic while code is trying to do a reset?

Do you mean PCI_COMMAND_MASTER rather than PCI_COMMAND_MEMORY? I tried
that too, it doesn't work either. I'm not really sure the theory
behind clearing memory, clearing busmaster to stop DMA seems like a
sane thing to do, but doesn't help here. Thanks,

Alex

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