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linux-usb-gadgets / libusbgx

C library encapsulating the Linux kernel USB gadget configfs userspace API functionality
GNU General Public License v2.0
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gt enable <gadget> returns error string: Failed to enable gadget Invalid parameter #58

Closed Dvergatal closed 2 years ago

Dvergatal commented 2 years ago

Just like in the subject the gt app returns error string Failed to enable gadget Invalid parameter. The error code USBG_ERROR_INVALID_PARAM is being returned from method _usbg_enablegadget in libusbgx/src/usbg.c. I have verified that it is being returned on no udc. I suspect that i am missing some kernel configuration for UDC, because even /sys/class/udc is empty. Correct me if i'm wrong, because i have no other clues.

pabs3 commented 2 years ago

Looking at the code, your analysis sounds correct.

The usbg_parse_udcs function fills in the udcs list from /sys/class/udc and if there are none then usbg_get_first_udc returns NULL and so usbg_enable_gadget will exit with USBG_ERROR_INVALID_PARAM.

If /sys/class/udc is empty then your Linux kernel version either doesn't have any UDC support compiled in (grep for UDC in your Linux kernel build config), or your device doesn't have any UDC hardware (you can use the dummy UDC to workaround that).

https://www.collabora.com/news-and-blog/blog/2019/06/24/using-dummy-hcd/

Which device do you have?

Which UDC hardware does your device have?

Which version of the Linux kernel do you use?

Which Linux kernel build config are you using?

Which version of libusbgx/gt are you using?

If you build (with CONFIG_USB_DUMMY_HCD=m) and load the dummy UDC (modprobe dummy_hcd), does libusbgx and gt work?

Arguably usbg_enable_gadget should return a value other than USBG_ERROR_INVALID_PARAM for situations where no UDC is available, would you be interested in helping contribute a patch for this?

-- bye, pabs

https://bonedaddy.net/pabs3/

Dvergatal commented 2 years ago

Hi @pabs3, i'm using firefly-rk3399 and with old 4.4.194 rockchip kernel, it was working alright. Now i have switched to 5.4.18 because of WPA3 support in it. I can debug which udc it was by switching to old kernel image. and also check your suggestion. Btw. yes i can help in cotribute a patch for this.

Dvergatal commented 2 years ago

Ok i have found out that with an older kernel i have this fe800000.dwc3 -> ../../devices/platform/usb0/fe800000.dwc3/udc/fe800000.dwc3 in older kernel but i have dwc3 support added in kernel 5.4.18 so i don't know what i can be missing.

Ok i think i know now. dwc3 is missing in dts files. No it is in it but the name has changed... hmm so i dunno. It should be working out of the box.

pabs3 commented 2 years ago

Seems like all the dwc3 and Firefly stuff is merged into Linux mainline, so it is probably a build issue or module loading issue. Can you check if you have CONFIG_USB_DWC3 and other related options enabled in your Linux kernel build config? Also check if any of the dwc3 modules are loaded or not loaded. Also check dmesg/journal for errors.

If you want to modify libusbgx or gt, please submit the patches as GitHub pull requests on the corresponding projects.

-- bye, pabs

https://bonedaddy.net/pabs3/

Dvergatal commented 2 years ago

BTW. sorry for not answering first your questions.

Which device do you have? firefly-rk3399

Which UDC hardware does your device have? fe800000.dwc3

Which version of the Linux kernel do you use? 5.4.18

Which Linux kernel build config are you using? defconfig for arm64

Which version of libusbgx/gt are you using? libusbgx-0.2.0 gt-afe7d8550ad1f0d6c97deefd645824b98397e33e from andrzejtp github

If you build (with CONFIG_USB_DUMMY_HCD=m) and load the dummy UDC (modprobe dummy_hcd), does libusbgx and gt work? Not tried it yet.

And i have been talking yesterday on irc with @mmind and he told me that there is a driver issue. On vendor kernel which is 4.4.194 rockchip team hacked that extcon thingy into the fusb302 driver, but that is of course no viable solution for mainline. For 5.4.18 i need to write a patch in which i will use the type-c framework in phy_rockchip_typec driver wich will know to use typec_fusb302 to make a call to dwc3. So i think we can close this issue.

pabs3 commented 2 years ago

Thanks for tracking the issue down, good luck with the driver fixes, closing this issue.

@Dvergatal If you are planning on writing a patch clarifying the libusbgx/gt error when no UDC is available, that would be great. Otherwise please file a separate issue for that and someone else will take care of it at some point.