Re: [PATCH v3 2/2] PCI: pciehp: Clear the optional capabilities in DEVCTL2 on a hot-plug

[Jay Cornwall <jay.cornwall@amd.com>]

On 6/22/2023 16:42, Lukas Wunner wrote:

> I don't now why commit 430a23689dea, which introduced
> pci_enable_atomic_ops_to_root(), chose to add it as a library function
> which is only called from specific drivers, instead of universally
> enabling the feature for all devices.  Adding the commit authors to cc
> so they can chime in.

IIRC during the initial design discussion on linux-pci this approach was suggested to avoid triggering potential bugs in devices without AtomicOps support. See quote below.

I've no objections to changing it.

On 2016-05-06 10:48, Bjorn Helgaas wrote:

> Once enabled in Device Control 2, a device's use of AtomicOps is
> competely device-specific.  In many cases, the device probably doesn't
> support AtomicOps, so enabling them would be a no-op.  But there could
> be devices where AtomicOps are nominally supported but untested or
> broken.  Even if we didn't change their drivers, those devices could
> start using AtomicOps, so I'm not comfortable with the PCI core
> enabling AtomicOp requests indiscriminately.