Hi Alan,
On Sat, 23 Apr 2022, Alan Stern wrote:
This patch adds a "gadget" bus and uses it for registering gadgets and
their drivers. From now on, bindings will be managed by the driver
core rather than through ad-hoc manipulations in the UDC core.
As part of this change, the driver_pending_list is removed. The UDC
core won't need to keep track of unbound drivers for later binding,
because the driver core handles all of that for us.
However, we do need one new feature: a way to prevent gadget drivers
from being bound to more than one gadget at a time. The existing code
does this automatically, but the driver core doesn't -- it's perfectly
happy to bind a single driver to all the matching devices on the bus.
The patch adds a new bitflag to the usb_gadget_driver structure for
this purpose.
A nice side effect of this change is a reduction in the total lines of
code, since now the driver core will do part of the work that the UDC
used to do.
A possible future patch could add udc devices to the gadget bus, say
as a separate device type.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Thanks for your patch, which is now commit fc274c1e997314bf ("USB:
gadget: Add a new bus for gadgets") in usb-next.
This patch cause a regression on the Renesas Salvator-XS development
board, as R-Car H3 has multiple USB gadget devices:
sysfs: cannot create duplicate filename '/bus/gadget/devices/gadget'
CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.18.0-rc1-arm64-renesas-00074-gfc274c1e9973 #1587
Hardware name: Renesas Salvator-X 2nd version board based on r8a77951 (DT)
Call trace:
dump_backtrace+0xcc/0xd8
show_stack+0x14/0x30
dump_stack_lvl+0x88/0xb0
dump_stack+0x14/0x2c
sysfs_warn_dup+0x60/0x78
sysfs_do_create_link_sd.isra.0+0xe4/0xf0
sysfs_create_link+0x20/0x40
bus_add_device+0x64/0x110
device_add+0x31c/0x850
usb_add_gadget+0x124/0x1a0
usb_add_gadget_udc_release+0x1c/0x50
usb_add_gadget_udc+0x10/0x18
renesas_usb3_probe+0x450/0x728
platform_probe+0x64/0xd0
really_probe+0x100/0x2a0
__driver_probe_device+0x74/0xd8
driver_probe_device+0x3c/0xe0
__driver_attach+0x80/0x110
bus_for_each_dev+0x6c/0xc0
driver_attach+0x20/0x28
bus_add_driver+0x138/0x1e0
driver_register+0x60/0x110
__platform_driver_register+0x24/0x30
renesas_usb3_driver_init+0x18/0x20
do_one_initcall+0x15c/0x31c
kernel_init_freeable+0x2f0/0x354
kernel_init+0x20/0x120
ret_from_fork+0x10/0x20
renesas_usb3: probe of ee020000.usb failed with error -17
...
renesas_usbhs: probe of e6590000.usb failed with error -17
After boot-up, only one gadget device is visible:
root@h3-salvator-xs:~# ls -l /sys/bus/gadget/devices/
total 0
lrwxrwxrwx 1 root root 0 Feb 14 2019 gadget -> ../../../devices/platform/soc/e659c000.usb/gadget
root@h3-salvator-xs:~#
Reverting this patch fixes the issue.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
