Re: [PATCH] net/nfp: support 48-bit DMA address for firmware with NFDk

[Kevin Traynor <ktraynor@redhat.com>]

On 15/02/2023 18:28, Ferruh Yigit wrote:
> On 2/15/2023 5:47 PM, Niklas Söderlund wrote:
>> Hi Ferruh,
>>
>> Thanks for your continues effort in dealing with NFP patches.
>>
>> On 2023-02-15 13:42:01 +0000, Ferruh Yigit wrote:
>>> On 2/8/2023 9:15 AM, Chaoyong He wrote:
>>>> From: Peng Zhang <peng.zhang@corigine.com>
>>>>
>>>> 48-bit DMA address is supported in the firmware with NFDk, so enable
>>>> this feature in PMD now. But the firmware with NFD3 still just
>>>> support 40-bit DMA address.
>>>>
>>>> RX free list descriptor, used by both NFD3 and NFDk, is also modified
>>>> to support 48-bit DMA address. That's OK because the top bits is always
>>>> set to 0 when assigned with 40-bit DMA address.
>>>>
>>>> Fixes: c73dced48c8c ("net/nfp: add NFDk Tx")
>>>> Cc: jin.liu@corigine.com
>>>> Cc: stable@dpdk.org
>>>>
>>>
>>> Why a backport is requested? As far as I understand this is not fixing
>>> anything but extending device capability. Is this a fix?
>>
>> I agree this is a bit of a grey zone. We reasoned this was a fix as we
>> should have done this from the start in the commit that added support
>> for NFDk. Are you OK moving forward with this as a fix or would you
>> prefer we resubmit without the request to backport?
>>
> 
> I am not sure, is this change have any potential to change behavior for
> existing users?
> Like if one of your user is using 22.11.1 release, and if this patch
> backported to next LTS version, 22.11.2, will user notice any difference?
> 
> 
> @Luca, @Kevin, what is your comment as LTS maintainers?
> 

A bit difficult to know. If NFDk is not practicably usable without it, 
then it could be considered a fix. If it's just extending to add 
nice-to-have functionality then probably it is not a fix.

It would need to ensure that it is tested on 22.11 branch and there are 
no regressions. It is only relevant to DPDK 22.11 LTS so Cc Xueming who 
will ultimately decide.

A guide below on some things to consider for this type of backport is here:
http://doc.dpdk.org/guides/contributing/stable.html#what-changes-should-be-backported

>>>
>>>> Signed-off-by: Peng Zhang <peng.zhang@corigine.com>
>>>> Reviewed-by: Chaoyong He <chaoyong.he@corigine.com>
>>>> Reviewed-by: Niklas Söderlund <niklas.soderlund@corigine.com>
>>>
>>
>