Re: [Suspected Spam] Re: [PATCH for-rc] RDMA/vmw_pvrdma: Fix the active_speed and phys_state value

[Adit Ranadive <aditr@vmware.com>]

On 11/2/20 10:27 AM, Jason Gunthorpe wrote:
> On Mon, Nov 02, 2020 at 10:21:21AM -0800, Adit Ranadive wrote:
>> On 11/2/20 10:02 AM, Jason Gunthorpe wrote:
>>> On Mon, Nov 02, 2020 at 09:55:25AM -0800, Adit Ranadive wrote:
>>>> On 10/29/20 9:16 AM, Adit Ranadive wrote:
>>>>> On 10/29/20 4:57 AM, Jason Gunthorpe wrote:
>>>>>> On Wed, Oct 28, 2020 at 11:19:45PM +0000, Adit Ranadive wrote:
>>>>>>> The PVRDMA device still reports the active_speed in u8.
>>>>>>> Lets use the ib_eth_get_speed to report the speed and
>>>>>>> width. Unfortunately, phys_state gets stored as msb of
>>>>>>> the new u16 active_speed.
>>>>>>
>>>>>> This explanation is not clear, I have no idea what this is fixing
>>>>>
>>>>> It seemed more clear to me in my head, I guess :).
>>>>>
>>>>> After commit 376ceb31ff87 changed the active_speed attribute to
>>>>> u16, both the active_speed and phys_state attributes in the
>>>>> pvrdma_port_attr struct are getting stored in this u16. As a 
>>>>> result, these show up as invalid values in ibv_devinfo.
>>>>>
>>>>> Our device still gives us back a u8 active_speed so both these
>>>>> are getting stored in the u16. This fix I proposed simply gets 
>>>>> the active_speed from the netdev while the phys_state still 
>>>>> needs to come from the pvrdma device, i.e. the msb the of the
>>>>> u16. I also removed some unused functions as a result.
>>>>>
>>>>> Alternatively, I could change the u8 active_width and u16 
>>>>> active_speed to reserved now that we're getting the active_speed
>>>>> and active_width from the ib_get_eth_speed function.
>>>>
>>>> Jason, did you have any comments on this or did you want me
>>>> to just send v1 with an updated description?
>>>
>>> I still haven't figured out what this is fixing.
>>>
>>> Is 'struct pvrdma_port_attr' some kind of ABI? If so why isn't the fix
>>> to revert the type?
>>
>> I can revert it but I thought that it had to a u16 based on the IBTA, no?
>> Or does that not apply to device-level stuff?
> 
> You didn't answer the question, it it ABI to some kind of FW interface
> or something?
> 
> *HOW* did two fields get overlapped onto a single u16?? The compiler
> won't do this..
> 

It is an ABI to the device for port attributes. The device gives us back
this structure for query port verb. The response from the device is
memcopied into this pvrdma_port_attr structure. So both the bytes 
representing active_speed and phys_state from the device are copied 
into the single u16 in this structure.