Re: dwc3 gadget and USB3

[Joakim Tjernlund <Joakim.Tjernlund@infinera.com>]

On Fri, 2023-03-10 at 22:58 +0000, Thinh Nguyen wrote:
> On Fri, Mar 10, 2023, Joakim Tjernlund wrote:
> > On Thu, 2023-03-09 at 21:09 +0000, Thinh Nguyen wrote:
> > > On Thu, Mar 09, 2023, Joakim Tjernlund wrote:
> > > > On Thu, 2023-03-09 at 19:56 +0000, Thinh Nguyen wrote:
> > > > > On Thu, Mar 09, 2023, Joakim Tjernlund wrote:
> > > > > > On Thu, 2023-03-09 at 17:32 +0100, Joakim Tjernlund wrote:
> > > > > > > On Wed, 2023-03-08 at 22:26 +0100, Joakim Tjernlund wrote:
> > > > > > > > On Wed, 2023-03-08 at 19:58 +0100, gregkh@linuxfoundation.org wrote:
> > > > > > > > > On Wed, Mar 08, 2023 at 06:12:51PM +0000, Joakim Tjernlund wrote:
> > > > > > > > > > On Wed, 2023-03-08 at 18:25 +0100, Greg KH wrote:
> > > > > > > > > > > On Wed, Mar 08, 2023 at 05:10:17PM +0000, Joakim Tjernlund wrote:
> > > > > > > > > > > 
> 
SNIP ...

> > 
> > 
> > While I remember, I tried to create both a NCM and a ttyACM on top of my dwc3 gadget
> > but then I got som bind error when activating the UDC. Is that expected ?
> > I figured both could live on the same device and would just mux the two protocols.
> > 
> 
> I'm not clear what you meant here. The gadget driver and the UDC driver
> should be separated and abstracted from each other.
> 
> Also, please note that all this talking points are based on the
> assumption that the issue is due to the host putting the device in
> suspend base on your experiment. We didn't review the logs.
> 
> IMO, the best option should be to prevent suspend from the host side as
> it looks like your device may operate in usb3 speed also?
> 
> BR,
> Thinh

This script best explain I think:
#! /bin/sh

stop() {
    g="/sys/kernel/config/usb_gadget/g1"
    if [ -e "${g}"/UDC ]; then
	echo "" >  "${g}"/UDC
	rm -f "${g}"/os_desc/c.1
	rm -f "${g}"/configs/c.1/ncm.usb0
	rm -f "${g}"/configs/c.1/acm.GS0
	[ -d "${g}"/configs/c.1/strings/0x409 ] && rmdir "${g}"/configs/c.1/strings/0x409
	[ -d "${g}"/functions/acm.GS0 ] && rmdir "${g}"/functions/acm.GS0
	[ -d "${g}"/functions/ncm.usb0 ] && rmdir "${g}"/functions/ncm.usb0
	[ -d "${g}"/c.1/strings ] && rmdir "${g}"/c.1/strings
	[ -d "${g}"/c.1/strings/0x409 ] && rmdir "${g}"/c.1/strings/0x409
	[ -d "${g}"/configs/c.1 ] && rmdir "${g}"/configs/c.1
	[ -d "${g}" ] && rmdir  "${g}"
    fi
}

start() {
    mkdir -p /sys/kernel/config/usb_gadget/g1
    cd /sys/kernel/config/usb_gadget/g1

    ###############################
    # Populate Device-Level Stuff #
    ###############################

    #Setting device class/subclass/protocol to these values
    # alerts the OS that this is a composite device with
    # IADs in it's firmware.
    # ref: https://docs.microsoft.com/en-us/windows-hardware/drivers/usbcon/usb-interface-association-descriptor
    echo "0xEF" > bDeviceClass
    echo "0x02" > bDeviceSubClass
    echo "0x01" > bDeviceProtocol

    echo "0x15A2" > idVendor
    echo "0x0001" > idProduct

    #mkdir strings/0x409
    #echo "1234567" > strings/0x409/serialnumber
    #echo "Infinera" > strings/0x409/manufacturer
    #echo "NDU" > strings/0x409/product

    #enable use of os_desc's (important for RNDIS & NCM enablement on Windows):
    echo 1       > os_desc/use
    echo 0xbc    > os_desc/b_vendor_code #or 0xcd ?
    echo MSFT100 > os_desc/qw_sign

    #################################
    # Populate Individual Functions #
    #################################

    #The order functions are populated here will be reflected in the
    # order of descriptors written.

    #########
    # RNDIS #
    #########
    #Note! If RNDIS is enabled, it *has* to be the first function! Otherwise, Windows 10 will report error 10 (failed to start device).
    # (It's unclear why this is the case..)
    # https://docs.microsoft.com/en-us/answers/questions/474108/does-rndis-need-to-be-listed-as-the-first-function.html
    # https://stackoverflow.com/questions/68365739/windows-rndis-compatible-device-does-rndis-need-to-be-listed-as-the-first-funct
    if [ 0 = 1 ]
    then
	mkdir functions/rndis.usb0
	mkdir -p functions/rndis.usb0/os_desc/interface.rndis

	# Set compatible / sub-compatible id's so that Windows can match this
	# function to RNDIS6 driver more easily.
	echo RNDIS   > functions/rndis.usb0/os_desc/interface.rndis/compatible_id
	echo 5162001 > functions/rndis.usb0/os_desc/interface.rndis/sub_compatible_id

	mkdir -p configs/c.1
	mkdir -p configs/c.1/strings/0x409
	echo "0xC0" > configs/c.1/bmAttributes # Self powered
	echo "conf1" > configs/c.1/strings/0x409/configuration
	ln -s functions/rndis.usb0 configs/c.1
	if [ ! -L os_desc/c.1 ]
	then
	    ln -s configs/c.1 os_desc
	fi
    fi

    #########
    # NCM   #
    #########
    #Usually I test with *either* RNDIS or NCM enabled, but not both, hence the if(0) here..
    if [ 1 = 1 ]
    then
	mkdir functions/ncm.usb0
	mkdir -p functions/ncm.usb0/os_desc/interface.ncm
	# Set compatible id so that Windows 10 can match this function to
	# NCM driver more easily.
	echo WINNCM   > functions/ncm.usb0/os_desc/interface.ncm/compatible_id

	mkdir -p configs/c.1
	mkdir -p configs/c.1/strings/0x409
	echo "0xC0" > configs/c.1/bmAttributes # Self powered
	echo "conf1" > configs/c.1/strings/0x409/configuration
	ln -s functions/ncm.usb0 configs/c.1
	if [ ! -L os_desc/c.1 ]
	then
	    ln -s configs/c.1 os_desc
	fi
    fi

    #########
    # ACM   #
    #########
    if [ 1 = 1 ]
    then
	mkdir -p functions/acm.GS0

	mkdir -p configs/c.1
	mkdir -p configs/c.1/strings/0x409
	echo "0xC0" > configs/c.1/bmAttributes # Self powered
	ln -fs functions/acm.GS0 configs/c.1
	if [ ! -L os_desc/c.1 ]
	then
	    ln -s configs/c.1 os_desc
	fi
    fi

    #Activate/bind USB gadget
    echo 2f00000.usb > UDC
}
command=$@

case ${command} in
    start)
	echo "Starting usb-lc"
	start
	#ifconfig lc 169.254.100.101 netmask 255.255.255.252 # for debug
    ;;
    stop)
	echo "Stopping usb-lc"
	stop
    ;;
    restart)
	stop
	start
	;;

    *)
	echo "Create USB Gadget device dual NCM and rndis V0.1.1 for MAC, Linux and Windows"
	exit 1
	;;
esac


This gives me an error:

./config_gadget.sh start
Starting usb-lc
sh: write error: Device or resource busy

the line causing that is:
echo 2f00000.usb > UDC

Just create either NCM or ACM works, but not both