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From:   Kalle Valo <kvalo@codeaurora.org>
To:     Brian Norris <briannorris@chromium.org>
Cc:     Carl Huang <cjhuang@codeaurora.org>,
        Abhishek Kumar <kuabhs@google.com>,
        linux-wireless <linux-wireless@vger.kernel.org>,
        ath11k@lists.infradead.org, ath10k <ath10k@lists.infradead.org>,
        Doug Anderson <dianders@chromium.org>
Subject: Re: [RFC 1/2] nl80211: add common API to configure SAR power limitations.
References: <1600753017-4614-1-git-send-email-cjhuang@codeaurora.org>
        <CA+ASDXM7TcF-zfbktbdSu-fDBuGe0LAgFq3Qt2zaq6efbWJ=sA@mail.gmail.com>
        <f3be456c4c748f21836279eb4dc16e5e@codeaurora.org>
        <CA+ASDXNaLvtJyY9_ds9RVL9VTkiYzChsGJS1czhVt-RKitCk5g@mail.gmail.com>
Date:   Thu, 05 Nov 2020 10:35:56 +0200
In-Reply-To: <CA+ASDXNaLvtJyY9_ds9RVL9VTkiYzChsGJS1czhVt-RKitCk5g@mail.gmail.com>
        (Brian Norris's message of "Wed, 4 Nov 2020 09:44:55 -0800")
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Brian Norris <briannorris@chromium.org> writes:

> + ath10k
>
> [ I realize I replied to the "wrong" RFC v1; I fell trap to Kalle's note:
>
> "When you submit a new version mark it as "v2". Otherwise people don't
> know what's the latest version." ]
>
> On Tue, Nov 3, 2020 at 11:32 PM Carl Huang <cjhuang@codeaurora.org> wrote:
>> On 2020-11-04 10:00, Brian Norris wrote:
>> > What are the ABI guarantees around a given driver/chip's 'sar_capa'?
>> > Do we guarantee that if the driver supports N ranges of certain bands,
>> > that it will always continue to support those bands?
> ...
>> For a given chip(at least a QCOM chip), we don't see that the
>> range will grow or change.
>
> That's good to know. But that's not quite the same as an ABI guarantee.

I'm not sure if I understood Brian's question correctly, but I have
concerns on the assumption that frequency ranges never change. For
example, in ath10k we have a patch[1] under discussion which adds more
channels and in ath11k we added 6 GHz band after initial ath11k support
landed. And I would not be surprised if in some boards/platforms a
certain band is disabled due to cotting costs (no antenna etc). My
preference is to have a robust interface which would be designed to
handle these kind of changes.

[1] [PATCH] ath10k: enable advertising support for channels 32, 68 and 98

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