usb: gadget: udc: renesas_usb3: add a safety connection way for forced_b_device

Browse source

This patch adds a safety connection way for "forced_b_device" with
"workaround_for_vbus" like below:

< Example for R-Car E3 Ebisu >
 # modprobe <any usb gadget driver>
 # echo 1 > /sys/kernel/debug/ee020000.usb/b_device
 (connect a usb cable to host side.)
 # echo 2 > /sys/kernel/debug/ee020000.usb/b_device

Previous code should have connected a usb cable before the "b_device"
is set to 1 on the Ebisu board. However, if xHCI driver on the board
is probed, it causes some troubles:
 - Conflicts USB VBUS/signals between the board and another host.
 - "Cannot enable. Maybe the USB cable is bad?" might happen on
   both the board and another host with a usb hub.
 - Cannot enumerate a usb gadget correctly because an interruption
   of VBUS change happens unexpectedly.

Reported-by: Kazuya Mizuguchi <kazuya.mizuguchi.ks@renesas.com>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

...

This commit is contained in:

Yoshihiro Shimoda 2018-11-09 20:44:36 +09:00 • committed by Felipe Balbi

parent 268784ba14

commit ceb94bc52c

1 changed files with 10 additions and 5 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

15

drivers/usb/gadget/udc/renesas_usb3.c

View file