Re: [PATCH 2/2] PCI: NVMe device specific reset quirk

[Keith Busch]

On Mon, Jul 23, 2018 at 04:24:31PM -0600, Alex Williamson wrote:
> Take advantage of NVMe devices using a standard interface to quiesce
> the controller prior to reset, including device specific delays before
> and after that reset.  This resolves several NVMe device assignment
> scenarios with two different vendors.  The Intel DC P3700 controller
> has been shown to only work as a VM boot device on the initial VM
> startup, failing after reset or reboot, and also fails to initialize
> after hot-plug into a VM.  Adding a delay after FLR resolves these
> cases.  The Samsung SM961/PM961 (960 EVO) sometimes fails to return
> from FLR with the PCI config space reading back as -1.  A reproducible
> instance of this behavior is resolved by clearing the enable bit in
> the configuration register and waiting for the ready status to clear
> (disabling the NVMe controller) prior to FLR.
> 
> As all NVMe devices make use of this standard interface and the NVMe
> specification also requires PCIe FLR support, we can apply this quirk
> to all devices with matching class code.

Shouldn't this go in the nvme driver's reset_prepare/reset_done callbacks?