linux-kernel - Re: [PATCH] wilc1000: Allow setting power

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Message-ID: <5378e756-8173-4c63-1f0d-e5836b235a48@microchip.com>
Date:   Wed, 15 Dec 2021 13:01:28 +0000
From:   <Ajay.Kathat@...rochip.com>
To:     <davidm@...uge.net>
CC:     <Claudiu.Beznea@...rochip.com>, <kvalo@...eaurora.org>,
        <davem@...emloft.net>, <kuba@...nel.org>,
        <linux-wireless@...r.kernel.org>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] wilc1000: Allow setting power_save before driver is
 initialized

On 13/12/21 02:50, David Mosberger-Tang wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>
> Unfortunately, this patch doesn't seem to be sufficient.  From what I
> can tell, if power-save mode is turned on before a station is
> associated with an access-point, there is no actual power savings.  If
> I issue the command after the station is associated, it works perfectly
> fine.
>
> Ajay, does this make sense to you?

I think the patch has no effect because wilc_init_fw_config() gets 
called before wilc_set_power_mgmt().

Also, you had mentioned that to enable the PSM(power-save mode), the 
toggling of PS mode is required that means the previous set_power_mgmt() 
was successful. I believe ".set_power_mgmt" cfg80211_ops doesn't get 
called when there is no change from the previous state.

Power-save mode is allowed to be enabled irrespective of station 
association state. Before association, the power consumption should be 
less with PSM enabled compared to PSM disabled. The WLAN automatic power 
save delivery gets enabled after the association with AP.

To check the power measurement before association,  test without 
wpa_supplicant.

Steps:
- load the module
- ifconfig wlan0 up
- iw dev wlan0 set power_save off (check the pwr measurement after PS 
mode disabled)
- iw dev wlan0 set power_save on (check the pwr measurement after PS 
mode enable)

Regards,
Ajay