linux-kernel - Re: [PATCH 1/2] wifi: mt76: mt7921: Disable powersaving by default

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Date:   Wed, 13 Dec 2023 13:27:38 -0600
From:   Mario Limonciello <mario.limonciello@....com>
To:     Ben Greear <greearb@...delatech.com>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Kalle Valo <kvalo@...nel.org>
Cc:     Felix Fietkau <nbd@....name>, Ryder Lee <ryder.lee@...iatek.com>,
        Shayne Chen <shayne.chen@...iatek.com>,
        Sean Wang <sean.wang@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Deren Wu <deren.wu@...iatek.com>,
        Ming Yen Hsieh <mingyen.hsieh@...iatek.com>,
        "open list:MEDIATEK MT76 WIRELESS LAN DRIVER" 
        <linux-wireless@...r.kernel.org>,
        "open list:ARM/Mediatek SoC support" <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        Sultan Alsawaf <sultan@...neltoast.com>
Subject: Re: [PATCH 1/2] wifi: mt76: mt7921: Disable powersaving by default

On 12/13/2023 08:45, Ben Greear wrote:
> On 12/13/23 5:26 AM, Lorenzo Bianconi wrote:
>>> Mario Limonciello <mario.limonciello@....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.
>>>
>>>> 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?
>>>
>>>> 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')
>>>
>>> * 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.
>>
>> agree, I think we do not need a new parameter for this, just use the 
>> current
>> APIs.
> 
> Is there a convenient way for a user to make any of those options above 
> stick through
> reboots?
> 
> To me, the ability to set system defaults through reboots is a nice 
> feature of
> module options.
> 
> Thanks,
> Ben
> 

Some userspace has the ability to do this.  For example in Network Manager:

https://unix.stackexchange.com/questions/595116/wi-fi-powersaving-in-networkmanager