[PATCH 1/2] nl80211: vendor-cmd: qca: add dynamic SAR power limits

Kalle Valo kvalo at codeaurora.org
Fri Jul 24 05:26:16 EDT 2020

Brian Norris <briannorris at chromium.org> writes:

> On Thu, Jul 16, 2020 at 2:35 AM Kalle Valo <kvalo at codeaurora.org> wrote:
>> Brian Norris <briannorris at chromium.org> writes:
>> > Really, I could live with per-vendor APIs. My primary goal is to get
>> > these upstream in some form, so vendors can stop using things like
>> > this as a reason for shipping us non-upstream code, and so we can
>> > reduce the delta between upstream and Chrome OS kernels.
>> >
>> > I also think that, for the cases that warrant it (i.e., the option 2
>> > -- Realtek and Qualcomm cases, so far), it would be good to have a
>> > common API, but that's a somewhat secondary concern for me.
>> So to me it feels like the best solution forward is to go with the
>> vendor API, do you agree? We can, of course, later switch to the common
>> API if we manage to create one which is usable for everyone.
> That's fine with me. That's pretty much what I said in my first email:
> "Anyway, I don't really object with starting out with a
> Qualcomm-specific and a Realtek-specific vendor command to implement
> nearly the same feature, but I'd prefer if people did engage in some
> healthy discussion about why they can't share an API, with the hopes
> that maybe they can converge someday."
> I think we've had some healthy (though very protracted) discussion,
> and I don't think I've seen anyone bring up anything I wasn't already
> aware of that would prevent eventual consolidation. As long as we
> acknowledge those things (item 2 at
> https://wireless.wiki.kernel.org/en/developers/documentation/nl80211#vendor-specific_api),
> I'm happy.

Good, I was just checking that we all are on the same page.

>> > Also, Kalle had some concerns about stable ABI questions: shouldn't we
>> > bake in some kind of "check for support" feature to these kinds of
>> > APIs [3]? That would help ease transition, if we do start with a
>> > vendor API and move to a common one in the future.
>> Yeah, that sounds like a good idea but I don't think that should block
>> these patches.
> OK, well it was your concern first, IIRC :)

I was commenting about the "check for support" feature :) I think it
would be a good idea to have userspace check what vendor interface
features/commands are supported with that driver/hardware/firmware
combo. But how should that be implemented? Should there be a some kind
of generic mechanism used by all drivers or would each driver have their
own method to check the supported features? I think that needs a
separate discussion.

> So what's next? A v2 that only needs a bit of updated description
> about "why a vendor API"?

I'm busy but hopefully Wen (CCed) can submit v2. Wen?

> And Realtek can feel free to submit this [1] shortly?

> [1] Series: rtw88: Add SAR implementation
> https://patchwork.kernel.org/project/linux-wireless/list/?series=238219&state=*

Yeah, please submit that as well.


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