[PATCH 1/2] wifi: mt76: mt7921: Disable powersaving by default
Mario Limonciello
mario.limonciello at amd.com
Wed Dec 13 11:26:22 PST 2023
On 12/13/2023 06:45, Kalle Valo wrote:
> Mario Limonciello <mario.limonciello at amd.com> writes:
>
>> Several users have reported awful latency when powersaving is enabled
>> with certain access point combinations.
>
> What APs are these exactly? In the past 802.11 Power Save Mode was
> challenging due to badly behaving APs. But nowadays with so many mobile
> devices in the market I would assume that APs work a lot better. It
> would be best to investigate the issues in detail and try to fix them in
> mt76, assuming the bugs are in mt76 driver or firmware.
In my case I could reproduce the behavior on my Unifi access points.
I've got a few that devices could roam between.
I also happen to have a laptop on my desk with a WCN6855 that behaves
just fine with those same APs.
The other people with problems I've asked to come to this thread to
share more about their devices.
>
>> It's also reported that the powersaving feature doesn't provide an
>> ample enough savings to justify being enabled by default with these
>> issues.
>
> Any numbers or how was this concluded?
It was just a data point in the original patch from Sultan (who is on
CC). I haven't corroborated it myself. Once I saw that other kernel
drivers like iwlwifi are also "defaulting" to off with a module
parameter I figured it made sense to bring that for discussion.
>
>> Introduce a module parameter that would control the power saving
>> behavior. Set it to default as disabled. This mirrors what some other
>> WLAN drivers like iwlwifi do.
>
> We have already several ways to control 802.11 power save mode:
>
> * NL80211_CMD_SET_POWER_SAVE (for example used by 'iw set power_save')
I'll experiment with an unpatched kernel just undoing this from here to
see if it alone improves things.
>
> * CONFIG_CFG80211_DEFAULT_PS (for kernel level default)
>
> * WIPHY_FLAG_PS_ON_BY_DEFAULT (for the driver to control the default setting)
>
> Adding module parameters as a fourth method sounds confusing so not
> really a fan of this. And the bar is quite high for adding new module
> parameters anyway.
>
Should we also discuss removing the iwlwifi one then too perhaps?
Seems incongruent to offer it for some drivers but not others.
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