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Subject: Re: [PATCH 1/2] wifi: mt76: mt7921: Disable powersaving by default
To: Lorenzo Bianconi <lorenzo@kernel.org>, Kalle Valo <kvalo@kernel.org>
Cc: Mario Limonciello <mario.limonciello@amd.com>,
 Felix Fietkau <nbd@nbd.name>, Ryder Lee <ryder.lee@mediatek.com>,
 Shayne Chen <shayne.chen@mediatek.com>, Sean Wang <sean.wang@mediatek.com>,
 Matthias Brugger <matthias.bgg@gmail.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>,
 Deren Wu <deren.wu@mediatek.com>, Ming Yen Hsieh
 <mingyen.hsieh@mediatek.com>,
 "open list:MEDIATEK MT76 WIRELESS LAN DRIVER"
 <linux-wireless@vger.kernel.org>,
 "open list:ARM/Mediatek SoC support" <linux-kernel@vger.kernel.org>,
 "moderated list:ARM/Mediatek SoC support"
 <linux-mediatek@lists.infradead.org>, Sultan Alsawaf <sultan@kerneltoast.com>
References: <20231212090852.162787-1-mario.limonciello@amd.com>
 <874jgmnud8.fsf@kernel.org> <ZXmxD1foASMaCDIe@lore-desk>
From: Ben Greear <greearb@candelatech.com>
Organization: Candela Technologies
Message-ID: <d92c081e-47dd-5c57-a6f1-bd72b2748141@candelatech.com>
Date: Wed, 13 Dec 2023 06:45:22 -0800
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On 12/13/23 5:26 AM, Lorenzo Bianconi wrote:
>> Mario Limonciello <mario.limonciello@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.
>>
>>> 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

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com