Re: Documentation for Raw USB ConfigFS

["Sid Spry" <sid@aeam.us>]

On Mon, May 18, 2020, at 12:48 AM, Peter Chen wrote:
> On 20-05-16 00:57:55, Sid Spry wrote:
> > On Thu, May 14, 2020, at 8:05 PM, Peter Chen wrote:
> > > 
> > > > >
> > > > > Would you please let ECM gadget work first at your board, then let
> > > > > f_fs work using test application (you need to compile both host and
> > > > > device application for it). After that, you may have more precise
> > > > > concept for Linux USB gadget framework.
> > > > >
> > > > 
> > > > I don't see anything that harmonizes preexsting function usage with specifying
> > > > custom endpoints.
> > > > 
> > > > I've gotten the ECM gadget, and then the ECM gadget via ffs working. I've read
> > > > through the ffs test but I don't see any way to assign functionality to the endpoints.
> > > > The example seems to transport raw data via a bulk endpoint. I know enough to
> > > > instead assign an isochronous endpoint to the UDC and transfer via that, but I don't
> > > > want it to be the *only* functionality the device offers.
> > > > 
> > > > Are you saying I can assign the ECM gadget via ffs and then add another driver
> > > > after the fact? 
> > > 
> > > ffs (f_fs.c) is used for customized function, other functions, like ECM (f_ecm.c)
> > > and Mass Storage (f_mass_storage.c) are used for certain function. You could
> > > use configfs (like you have done below) to put customized function and certain functions
> > > into one configuration, and let the host see them at the same time. Do your
> > > real requirement is one customized function and one ECM function in one USB gadget?
> > > If it is, below is the example to combine f_fs, mass_storage, and NCM together.
> > > 
> > > cd /sys/kernel/config/usb_gadget
> > > cd g1
> > > echo "0x1d6b" > idVendor
> > > echo "0x0105" > idProduct
> > > mkdir /dev/usb-ffs
> > > mkdir functions/ffs.usb
> > > mount -t functionfs usb /dev/usb-ffs
> > > ln -s functions/ffs.usb configs/c.1
> > > /home/root/usb_test/ffs_test/ffs-test & /* your own test application */
> > > while [ ! -e /dev/usb-ffs/ep1 ]
> > > do
> > >  echo "."
> > >  sleep 1;
> > > done
> > > mkdir functions/ncm.0 
> > > ln -s functions/ncm.0 configs/c.1 
> > > mkdir functions/mass_storage.0
> > > ln -s functions/mass_storage.0 configs/c.1
> > > echo $FILE > functions/mass_storage.0/lun.0/file 
> > > 
> > > Peter 
> > > 
> > 
> > Hi Peter, thanks for the advice. I realized I was confusing FunctionFS and ConfigFS a little while after I sent my message and saw the FFS configuration in the ConfigFS documentation.
> > 
> > And yes, I need ECM/NCM (one is newer and faster, will go look it up again) and my custom function. I may also include a serial port.
> > 
> > I have been having issues creating any file called "ffs.${id}" in the gadget directory. It fails with device or resource busy. I assume this means I have misconfigured it, but I am copying your example; or missing the driver, but I have ensured it is there.[1] I have also tried ensuring the ffs function is added first. Any pointers?
> > 
> 
> 1. Please build in all configfs functions, and choose through the
> script.
> 
> CONFIG_USB_CONFIGFS=y
> CONFIG_USB_CONFIGFS_SERIAL=y
> CONFIG_USB_CONFIGFS_ACM=y
> CONFIG_USB_CONFIGFS_OBEX=y
> CONFIG_USB_CONFIGFS_NCM=y
> CONFIG_USB_CONFIGFS_ECM=y
> CONFIG_USB_CONFIGFS_ECM_SUBSET=y
> CONFIG_USB_CONFIGFS_RNDIS=y
> CONFIG_USB_CONFIGFS_EEM=y
> CONFIG_USB_CONFIGFS_MASS_STORAGE=y
> CONFIG_USB_CONFIGFS_F_LB_SS=y
> CONFIG_USB_CONFIGFS_F_FS=y
> CONFIG_USB_CONFIGFS_F_UAC1=y
> CONFIG_USB_CONFIGFS_F_UAC1_LEGACY=y
> CONFIG_USB_CONFIGFS_F_UAC2=y
> CONFIG_USB_CONFIGFS_F_MIDI=y
> CONFIG_USB_CONFIGFS_F_HID=y
> CONFIG_USB_CONFIGFS_F_UVC=y
> 
> 2. Try exactly the same script I gave you, do not try change
> any charaters (except the position for your application)
> 
> > > cd /sys/kernel/config/usb_gadget
> > > cd g1
> > > echo "0x1d6b" > idVendor
> > > echo "0x0105" > idProduct
> > > mkdir /dev/usb-ffs
> > > mkdir functions/ffs.usb
> > > mount -t functionfs usb /dev/usb-ffs
> > > ln -s functions/ffs.usb configs/c.1
> > > /home/root/usb_test/ffs_test/ffs-test & /* your own test application */
> > > while [ ! -e /dev/usb-ffs/ep1 ]
> > > do
> > >  echo "."
> > >  sleep 1;
> > > done
> 
> > 
> > [1]: I actually did not have CONFIG_USB_CONFIGFS_F_FS nor F_NCM/ECM set however the necessary code seemed to have been pulled in some other way and the modules were available. They were loaded, and as explained my shell-based configfs code worked. They are set now and the problem persists.
> 

Hi, sorry I was not clear. The kernel config is fine, and CONFIG_USB_CONFIGFS_F_FS is set. I run your exact script (minus the ffs-test line) and it fails to create the functions/ffs.usb directory as I described before. I can create other functions just fine.