Re:Re: [RFC PATCH v2 0/6] net: wwan: add NMEA port type support

["Slark Xiao" <slark_xiao@163.com>]

At 2025-09-15 00:43:05, "Sergey Ryazanov" <ryazanov.s.a@gmail.com> wrote:
>Hi Slark,
>
>On 9/11/25 05:42, Slark Xiao wrote:
>> At 2025-06-30 15:30:14, "Loic Poulain" <loic.poulain@oss.qualcomm.com> wrote:
>>> On Sun, Jun 29, 2025 at 12:07 PM Sergey Ryazanov <ryazanov.s.a@gmail.com> wrote:
>>>> On 6/29/25 05:50, Loic Poulain wrote:
>>>>> On Tue, Jun 24, 2025 at 11:39 PM Sergey Ryazanov <ryazanov.s.a@gmail.com> wrote:
>>>>>> The series introduces a long discussed NMEA port type support for the
>>>>>> WWAN subsystem. There are two goals. From the WWAN driver perspective,
>>>>>> NMEA exported as any other port type (e.g. AT, MBIM, QMI, etc.). From
>>>>>> user space software perspective, the exported chardev belongs to the
>>>>>> GNSS class what makes it easy to distinguish desired port and the WWAN
>>>>>> device common to both NMEA and control (AT, MBIM, etc.) ports makes it
>>>>>> easy to locate a control port for the GNSS receiver activation.
>>>>>>
>>>>>> Done by exporting the NMEA port via the GNSS subsystem with the WWAN
>>>>>> core acting as proxy between the WWAN modem driver and the GNSS
>>>>>> subsystem.
>>>>>>
>>>>>> The series starts from a cleanup patch. Then two patches prepares the
>>>>>> WWAN core for the proxy style operation. Followed by a patch introding a
>>>>>> new WWNA port type, integration with the GNSS subsystem and demux. The
>>>>>> series ends with a couple of patches that introduce emulated EMEA port
>>>>>> to the WWAN HW simulator.
>>>>>>
>>>>>> The series is the product of the discussion with Loic about the pros and
>>>>>> cons of possible models and implementation. Also Muhammad and Slark did
>>>>>> a great job defining the problem, sharing the code and pushing me to
>>>>>> finish the implementation. Many thanks.
>>>>>>
>>>>>> Comments are welcomed.
>>>>>>
>>>>>> Slark, Muhammad, if this series suits you, feel free to bundle it with
>>>>>> the driver changes and (re-)send for final inclusion as a single series.
>>>>>>
>>>>>> Changes RFCv1->RFCv2:
>>>>>> * Uniformly use put_device() to release port memory. This made code less
>>>>>>     weird and way more clear. Thank you, Loic, for noticing and the fix
>>>>>>     discussion!
>>>>>
>>>>> I think you can now send that series without the RFC tag. It looks good to me.
>>>>
>>>> Thank you for reviewing it. Do you think it makes sense to introduce new
>>>> API without an actual user? Ok, we have two drivers potentially ready to
>>>> use GNSS port type, but they are not yet here. That is why I have send
>>>> as RFC. On another hand, testing with simulator has not revealed any
>>>> issue and GNSS port type implementation looks ready to be merged.
>>>
>>> Right, we need a proper user for it, I think some MHI PCIe modems already
>>> have this NMEA port available, so it can easily be added to this PR. For sure
>>> we will need someone to test this.
>>>
>> Hi Loic, Sergey,
>> Any update about this topic?
>> If you want to test it, we can provide some help on this. Also, I think the quicinc
>> center may also do some test. You can contact it with Mani for further details.
>
>Basically the functionality is done, Loic has reviewed it, while not 
>formally acked yet. And it can be merged just now. On another hand we 
>have no users for it. That is why I have not sent it as a final patch.
>
>I was expected you, Slark, or Muhammad will take these patches, 
>incorporate into a driver change that introduces NMEA port export and we 
>can merge all together. Or if you prefer this series being merged first 
>and then you will send your changes. In this case I need a green light 
>from you that you tested this series locally and there are no objections.
>
>To summarize, we have two options:
>a) you incorporate this series into your changes and send a bigger 
>series implementing everything from driver to the core;
>b) we merge this series as it is, and then you send an follow up changes 
>introducing a driver support.
>
>Slark, Muhammad, let me know, which way is more suitable for you.
>
>--
>Sergey

I would prefer to select option (b).
Basically there is no big problem in my local based on your V1 patches .
And I think it's hard to reach to 100% for a new feature. There must be have 
some extra patches to complete it.
How about your opinion, Mani?