netdev - Re: rfkill: wwan does not show up in rfkill command

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Message-ID: <87lez9w4f8.fsf@miraculix.mork.no>
Date:   Fri, 21 Jan 2022 15:26:35 +0100
From:   Bjørn Mork <bjorn@...k.no>
To:     Fabio Estevam <festevam@...il.com>
Cc:     Johannes Berg <johannes@...solutions.net>,
        netdev <netdev@...r.kernel.org>, Andrew Lunn <andrew@...n.ch>,
        Vladimir Oltean <vladimir.oltean@....com>
Subject: Re: rfkill: wwan does not show up in rfkill command

Fabio Estevam <festevam@...il.com> writes:

> Hi,
>
> I am running kernel 5.10.92 on an imx7d SoC.
>
> The wwan interface is brought up:
>
> usb 2-1: New USB device found, idVendor=2c7c, idProduct=0296, bcdDevice= 0.00
> usb 2-1: New USB device strings: Mfr=3, Product=2, SerialNumber=4
> usb 2-1: Product: Qualcomm CDMA Technologies MSM
> usb 2-1: Manufacturer: Qualcomm, Incorporated
> usb 2-1: SerialNumber: 7d1563c1
> option 2-1:1.0: GSM modem (1-port) converter detected
> usb 2-1: GSM modem (1-port) converter now attached to ttyUSB0
> option 2-1:1.1: GSM modem (1-port) converter detected
> usb 2-1: GSM modem (1-port) converter now attached to ttyUSB1
> option 2-1:1.2: GSM modem (1-port) converter detected
> usb 2-1: GSM modem (1-port) converter now attached to ttyUSB2
> option 2-1:1.3: GSM modem (1-port) converter detected
> usb 2-1: GSM modem (1-port) converter now attached to ttyUSB3
> qmi_wwan 2-1:1.4: cdc-wdm0: USB WDM device
> qmi_wwan 2-1:1.4 wwan0: register 'qmi_wwan' at usb-ci_hdrc.1-1,
> WWAN/QMI device, 0e:31:86:6b:xx:xx
>
> When I run the rfkill command, only the Wifi interface shows up:
>
> root@...0000000:~# rfkill
> ID TYPE DEVICE      SOFT      HARD
>  0 wlan phy0   unblocked unblocked
>
> Shouldn't the wwan interface also be listed in the rfkill output?

This is a platform issue IMHO.  The externail W_DISABLE input is the
only meaningful rfkill device.  Controlling it is platform specific,
independent of the modem hardware.

Mapping W_DISABLE to an rfkill device is by typically done be drivers
like this ACPI driver in my Thinkpad:

root@...aculix:/tmp# rfkill
ID TYPE      DEVICE                   SOFT      HARD
 0 bluetooth tpacpi_bluetooth_sw unblocked unblocked
 1 wwan      tpacpi_wwan_sw      unblocked unblocked
 2 wlan      phy0                unblocked unblocked
 3 bluetooth hci0                unblocked unblocked


In theory we could have had an rfkill implementation in the wwan
subsystem too, similar to that redundant hci0 rfkill.  But I don't think
it's currently going to fly, given that the modem radio typically is
managed by multiple distinct drivers (tty, net, ++).

> Is there anything that needs to be done for wwan to appear there?
>
> Also, there is a GPIO that connects to the modem (W_DISABLE) pin, but
> it seems it is not possible currently to use rkfill gpio with device
> tree, right? I saw some previous attempts to add rfkill gpio support
> in devicetree, but none was accepted.

This I don't know anything about...  But it does sound like a good
solution for any platfrom using DT and a W_DISABLE GPIO.  Wonder why
that wasn't accepted?


Bjørn