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SubjectRe: [PATCH] wilc1000: Allow setting power_save before driver is initialized
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On Thu, 2021-12-23 at 14:02 +0000, Ajay.Kathat@microchip.com wrote:
>
> I verified with wpa_supplicant and it seems the power save mode is
> working fine. Tested multiple times with wpa_supplicant running. I
> didn't observe any issue in entering or exiting the power-save mode with
> wpa_supplicant.
>
> Try to verify without wpa_supplicant in your setup to observe if we are
> seeing this same results in that case.

It doesn't help me if it works without wpa_supplicant. I need a
reliable way to have power-savings mode in effect when using
wpa_supplicant.

> With wpa_supplicant, the current consumption is less when PS mode is
> enabled but it would be more compared to without wpa_supplicant.

That's not what I'm talking about though. The problem is that it seems
to be rather erratic whether issuing the iw power_save command makes a
difference in power-consumption.

I fixed my setup so I can directly measure power consumed rather than
just current (power factor matters). Again, this is for the entire
device (not just WILC1000).

What I find that when power-saving mode is working as expected, the
device uses an average of 1.1W. When power-saving mode is not working,
power consumption is about 1.4W, or about 300mW higher.

I tried again *without* the patch applied and, as expected, the patch
doesn't really affect this behavior.

After playing with this for a while, I think I found two sequences that
reliably reproduce the difference.

First, on a freshly booted system and with wilc1000-spi autoloaded by
the kernel, try this sequence (copy & paste the commands):

/usr/sbin/wpa_supplicant -Bs -iwlan0 -c/etc/wpa_supplicant.conf
sleep 10
iw dev wlan0 set power_save on

The above yields a power consumption of 1.4W reliably. The "sleep 10"
doesn't matter here; the behavior is the same with or without it. I
tried waiting up to 120 seconds with no difference.

Second, on a freshly booted system and with wilc1000-spi autoloaded by
the kernel, try this sequence (copy & paste the commands):

/usr/sbin/wpa_supplicant -Bs -iwlan0 -c/etc/wpa_supplicant.conf
sleep 10
rmmod wilc1000-spi
modprobe wilc1000-spi
sleep 10
iw dev wlan0 set power_save on

The above yields a power consumption of 1.1W reliably.

Can you reproduce this, or, if not, share the power consumption you see
for the two cases?

--david


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