Re: [PATCH for-next 06/10] rdma: Set physical MTU for query_port function

[Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>]

On 4/8/2021 8:14 AM, Leon Romanovsky wrote:
> On Thu, Apr 08, 2021 at 08:06:46AM -0400, Dennis Dalessandro wrote:
>> On 4/1/2021 4:42 AM, Leon Romanovsky wrote:
>>> On Mon, Mar 29, 2021 at 09:54:12AM -0400, dennis.dalessandro@cornelisnetworks.com wrote:
>>>> From: Kaike Wan <kaike.wan@intel.com>
>>>>
>>>> This is a follow on patch to add a phys_mtu field to the
>>>> ib_port_attr structure to indicate the maximum physical MTU
>>>> the underlying device supports.
>>>>
>>>> Extends the following:
>>>> commit 6d72344cf6c4 ("IB/ipoib: Increase ipoib Datagram mode MTU's upper limit")
>>>>
>>>> Reviewed-by: Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com>
>>>> Signed-off-by: Kaike Wan <kaike.wan@intel.com>
>>>> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
>>>> ---
>>>>    drivers/infiniband/hw/bnxt_re/ib_verbs.c        |  1 +
>>>>    drivers/infiniband/hw/cxgb4/provider.c          |  1 +
>>>>    drivers/infiniband/hw/efa/efa_verbs.c           |  1 +
>>>>    drivers/infiniband/hw/hns/hns_roce_main.c       |  1 +
>>>>    drivers/infiniband/hw/i40iw/i40iw_verbs.c       |  1 +
>>>>    drivers/infiniband/hw/mlx4/main.c               |  1 +
>>>>    drivers/infiniband/hw/mlx5/mad.c                |  1 +
>>>>    drivers/infiniband/hw/mlx5/main.c               |  2 ++
>>>>    drivers/infiniband/hw/mthca/mthca_provider.c    |  1 +
>>>>    drivers/infiniband/hw/ocrdma/ocrdma_verbs.c     |  1 +
>>>>    drivers/infiniband/hw/qib/qib_verbs.c           |  1 +
>>>>    drivers/infiniband/hw/usnic/usnic_ib_verbs.c    |  1 +
>>>>    drivers/infiniband/hw/vmw_pvrdma/pvrdma_verbs.c |  1 +
>>>>    drivers/infiniband/sw/siw/siw_verbs.c           |  1 +
>>>>    drivers/infiniband/ulp/ipoib/ipoib_main.c       |  2 +-
>>>>    include/rdma/ib_verbs.h                         | 17 -----------------
>>>>    16 files changed, 16 insertions(+), 18 deletions(-)
>>>
>>> But why? What will it give us that almost all drivers have same
>>> props->phys_mtu = ib_mtu_enum_to_int(props->max_mtu); line?
>>>
>>
>> Almost is not all. Alternative idea to convey this? Seemed like a sensible
>> thing to at least have support for but open to other approaches.
> 
> What about leave it as is?
> 
> I'm struggling to get the rationale behind this patch., the code already works
> and set the phys_mtu correctly, isn't it?

I see what you are saying now. Kaike, correct me if I'm wrong, but the 
intent of this patch is just to make everything behave the same in the 
sense that a device could have a different physical MTU. The field got 
added to the ib_port_attr previously so this is giving it an initial 
value vs leaving it unset.

-Denny