[PATCH] powerpc/powernv/pci: Drop VF MPS fixup

[Michael Ellerman]

"Oliver O'Halloran" <oohall at gmail.com> writes:
> On Thu, May 19, 2022 at 10:38 PM Michael Ellerman <mpe at ellerman.id.au> wrote:
>> Christophe Leroy <christophe.leroy at csgroup.eu> writes:
>> > Le 02/09/2020 à 05:51, Oliver O'Halloran a écrit :
>> >> The MPS field in the VF config space is marked as reserved in current
>> >> versions of the SR-IOV spec. In other words, this fixup doesn't do
>> >> anything.
>> >>
>> >> Signed-off-by: Oliver O'Halloran <oohall at gmail.com>
>> >
>> > A lot of cleanup patches from Oliver were merged in Septembre 2020 but
>> > not this one.
>> >
>> > Any reason ?
>>
>> It wasn't clear to me that it's safe to remove. The commit that added it
>> seemed to think it was important.
>>
>> The fact that it's out-of-spec doesn't mean we don't have some hardware
>> somewhere that relies on that.
>
> There is no hardware that depends on it. It was added in response to a
> bug report on the IBM internal bugzilla about virtual functions not
> reporting the same MPS as the physical function in the output of
> lspci. This is by design since MPS is a property that is only relevant
> to the PF. There was a corresponding patch to skiboot to intercept
> writes to the MPS field of VFs which was used to fake a writable MPS
> field in firmware. I removed that hack in 2019
> (https://github.com/open-power/skiboot/commit/22057f868f3b2b1fd02647a738f6da0858b5eb6c)
> since it was pointless and was causing other problems. There's no real
> reason to keep this code around IMO.

Thanks for the extra detail, I am persuaded :)

cheers