netdev - Re: wilc1000 MAC address is 00:00:00:00:00:00

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Message-ID: <CAEyMn7YnqhbmOnKQkks5OkGwuKoBPkQkfuWWJ2s_GAEY9WP4Wg@mail.gmail.com>
Date:   Thu, 9 Feb 2023 19:40:14 +0100
From:   Heiko Thiery <heiko.thiery@...il.com>
To:     Ajay.Kathat@...rochip.com
Cc:     Claudiu.Beznea@...rochip.com, kvalo@...nel.org,
        linux-wireless@...r.kernel.org, michael@...le.cc,
        netdev@...r.kernel.org, Amisha.Patel@...rochip.com
Subject: Re: wilc1000 MAC address is 00:00:00:00:00:00

Hi,

Am Do., 9. Feb. 2023 um 18:15 Uhr schrieb <Ajay.Kathat@...rochip.com>:
>
> Hi Heiko,
>
> On 2/8/23 07:24, Heiko Thiery wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> >
> > Hi,
> >
> > I'm using the WILC1000 wifi and with NetworkManager [1] I see issues
> > in certain situations I see problems.
> >
> > I was able to reduce the problem and have now found out that the cause
> > is that the interface has the HW MAC address is 00:00:00:00:00 after
> > startup. Only when the interface is startup (ip link set dev wlan0
> > up), the driver sets a "valid" address.
> >
>
> IIUC network manager(NM) is trying to read the MAC address and write the
> same back to wilc1000 module without making the wlan0 interface up. right?

As far as I understand, network-manager will read the "real" HW
address. Then it sets a random
generated HW for scanning and after that switches back to the "real" HW address.

There seems to be circumstances where the wrong HW address
(00:00:00:00:00:00) is read and stored for
later reset after the scanning.

> Not sure about the requirement but if NM has a valid MAC address to
> assign to the wlan0 interface, it can be configured without making
> interface up("wlan0 up"). "ip link set dev wlan0 address XX:XX:XX:XX:XX"
> command should allow to set the mac address without making the interface
> up.
> Once the mac address is set, the wilc1000 will use that mac address [1]
> instead of the one from wilc1000 NV memory until reboot. However, after
> a reboot, if no MAC address is configured from application then wilc1000
> will use the address from its NV memory.
>
> > Is this a valid behavior and shouldn't the address already be set
> > after loading the driver?
> >
>
> Only when the interface is up(ifconfig wlan0 up), driver loads the
> firmware to wilc1000 module and after that the WID commands which allows
> to set/get the mac address from the wilc1000 works.

Is there a hard technical reason not to load the firmware and set the
HW address when
the driver is initialized and not only when its opened.

-- 
Heiko

>
> Regards,
> Ajay
>
> 1.
> https://github.com/torvalds/linux/blob/master/drivers/net/wireless/microchip/wilc1000/netdev.c#L600