Re: [PATCH] wilc1000: Allow setting power_save before driver is initialized

On Wed, 2021-12-15 at 13:01 +0000, Ajay.Kathat@microchip.com wrote:

On 13/12/21 02:50, David Mosberger-Tang wrote:

quoted

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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?

  <snip>
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)

It appears wpa_supplicant consistently renders PSM ineffective:

                                (current draw, 1 min avg):
------------------------------  --------------------------
- base case (no module loaded): 16.8 mA
- module loaded & PSM on      : 16.8 mA
- wpa_supplicant started      : 19.6 mA
- PSM on                      : 19.6 mA (no change)
- PSM off                     : 19.6 mA (no change)
- PSM on                      : 15.4 mA

What's strange is when I try this sequence a couple of times in a row,
the device gets into a state where after starting wpa_supplicant, no
amount of PSM on/off commands will get it to enter power-savings mode
any more.  When in that state, only removing wilc1000-spi.ko and adding
it back gets it out of that state.  A power-cycle does not.  Very
confusing.

  --david