g_ether missing eem support

[Enoch Leung]

I am looking into enabling EEM with g_ether by module option use_eem=1, and g_ether won't be loaded because it has no EEM support compiled.

Expected: EEM is compiled with g_ether (no such option for g_cdc) so that it can be enabled by use_eem=1.

My "/sys/module/g_ether/parameters":
-r--r--r-- 1 root root 4096 Feb 20 13:40 bcdDevice
-r--r--r-- 1 root root 4096 Feb 20 13:40 dev_addr
-r--r--r-- 1 root root 4096 Feb 20 13:40 host_addr
-r--r--r-- 1 root root 4096 Feb 20 13:40 iManufacturer
-r--r--r-- 1 root root 4096 Feb 20 13:40 iProduct
-r--r--r-- 1 root root 4096 Feb 20 13:40 iSerialNumber
-r--r--r-- 1 root root 4096 Feb 20 13:40 idProduct
-r--r--r-- 1 root root 4096 Feb 20 13:40 idVendor
-rw-r--r-- 1 root root 4096 Feb 20 14:08 qmult

modinfo g_ether:
parm: idVendor:USB Vendor ID (ushort)
parm: idProduct:USB Product ID (ushort)
parm: bcdDevice:USB Device version (BCD) (ushort)
parm: iSerialNumber:SerialNumber string (charp)
parm: iManufacturer:USB Manufacturer string (charp)
parm: iProduct:USB Product string (charp)
parm: qmult:queue length multiplier at high/super speed (uint)
parm: dev_addr:Device Ethernet Address (charp)
parm: host_addr:Host Ethernet Address (charp)
parm: use_eem:use CDC EEM mode (bool)

dmesg:
...
[ 4.474689] udc-core: couldn't find an available UDC - added [g_ether] to list of pending drivers
...
[ 5.768660] dwc2 fe980000.usb: EPs: 8, dedicated fifos, 4080 entries in SPRAM
[ 5.772414] g_ether fe980000.usb: failed to start g_ether: -2
...

---- should it be another bug? -----
There is another issue that when my laptop is connected and the with my Pi 4 reboot, the cdc_ether function provided to my laptop will not be available again until I reconnect the cable (I have USB Y-cable + type-c adapter so I can unplug on laptop side w/o Pi 4 losing power). I remember it was working as expected when I was testing out OTG function.

[Juerg Haefliger (juergh)]

What series/kernel is this?

[Hui Wang (hui.wang)]

at least, it is for eoan.

[Juerg Haefliger (juergh)]

Is this still an issue with a current focal image from http://cdimage.ubuntu.com/releases/20.04/release/?

[Enoch Leung (leun0036)]

Sorry I cannot tell, as the OTG issue just come back after I upgraded to Focal via do-release-upgrade. Pls. refer to bug #1861070

[Enoch Leung (leun0036)]

I just updated kernel to have OTG working again as per #1861070, and can tell that EEM support is still missing.

/sys/module/g_ether/parameters has no entry of use_eem has per "modinfo g_ether" mentioned. g_cdc / g_multi has no use_eem as per modinfo, and I am not sure if it is also a good place to ask for that being added to these two modules or not.

[Juerg Haefliger (juergh)]

/sys/module/g_ether/parameters/use_eem is not visible because the driver doesn't make it available to sysfs. That might be by design or a defect but it doesn't really matter here. EEM support is built-in and can be turned on by loading the driver with 'modprobe g_ether use_eem=1'.

Note that we will not add EEM support to any other drivers since that is a feature request which we typically don't allow for stable kernels.