linux-kernel - Re: [PATCH v2 2/2] wcn36xx: Implement tx

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Date:   Sun, 20 Mar 2022 21:15:25 +0200
From:   Kalle Valo <kvalo@...nel.org>
To:     Bryan O'Donoghue <bryan.odonoghue@...aro.org>
Cc:     Edmond Gagnon <egagnon@...areup.com>,
        Benjamin Li <benl@...areup.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, wcn36xx@...ts.infradead.org,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] wcn36xx: Implement tx_rate reporting

Bryan O'Donoghue <bryan.odonoghue@...aro.org> writes:

> On 20/03/2022 13:21, Bryan O'Donoghue wrote:
>> On 18/03/2022 19:58, Edmond Gagnon wrote:
>>> +    INIT_DELAYED_WORK(&wcn->get_stats_work, wcn36xx_get_stats_work);
>>
>> Instead of forking a worker and polling we could add the relevant
>> SMD command to
>>
>> static int wcn36xx_smd_tx_compl_ind(struct wcn36xx *wcn, void *buf,
>> size_t len)
>> {
>>      wcn36xx_smd_get_stats(wcn, 0xSomeMask);
>> }
>>
>> That way we only ever ask for and report a new TX data rate when we
>> know a TX event - and hence a potential TX data-rate update - has
>> taken place.
>>
>> ---
>> bod
>>
>
> Thinking a bit more
>
> - Do the SMD get_stats in the tx completion
>   This might be a problem initiating another SMD transaction inside
>   of an SMD callback. But is the most straight forward way to
>   get the data while avoiding alot of needless polling.
>
> - Schedule your worker from the TX completion
>   Again you should only care about gathering the data when you know
>   something has happened which necessitates gathering that data
>   like TX completion
>
> - Schedule your worker from the RX indication routine
>   Seems not as logical as the first two but it might be easier
>   to schedule the worker in the RX data handler
>
> Either way, I do think you should only gather this data on an event,
> not as a continuous poll.

I agree, a continuous poll is not a good idea as it affects power
consumption. What about struct ieee80211_ops::sta_statistics? AFAIK
that's called only when user space is requestings stats so the overhead
should be minimal.

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