dwc2: gadget mode and timeout with GRSTCTL_CSFTRST

[Heiko Stuebner <heiko.stuebner@theobroma-systems.com>]

Hi,

right now we're experiencing strange behaviour with a dwc2 on Rockchip's
PX30 soc.

With a cable connected to the port, the configfs-snippet below seems to
work and at least creates a acm device on the host. Though I'm told that a
	 picocom -b 115200 /dev/ttyACM
sometimes works ok but also sometimes returns -EBUSY or hangs.
[But I guess that is a separate problem]

But if there is no cable connected when trying to do the configfs steps
we end up with
	dwc2_core_reset: HANG! Soft Reset timeout GRSTCTL GRSTCTL_CSFTRST
and no gadget gets configured.


So I guess to get a feeling for the issue, is this something to be
expected, or at least a known issue, with maybe a fix flying around
somewhere?

Or is this working on other dwc2 platforms correctly and is caused
by some other part talking to the dwc2 doing strange things?


Thanks
Heiko

-------- 8< ---- configfs snippet ------ >8 --------
cd /configfs/usb_gadget
mkdir g1
cd g1
echo "0x1d6d" > idVendor
echo "0x0104" > idProduct
mkdir strings/0x409
echo "0123456789" > strings/0x409/serialnumber
echo "Theobroma Systems" > strings/0x409/manufacturer
echo "Cobra Debug Serial" > strings/0x409/product

# create config
mkdir configs/c.1
mkdir configs/c.1/strings/0x409
echo "conf1" > configs/c.1/strings/0x409/configuration

# create function
mkdir functions/acm.usb0
ln -s functions/acm.usb0 configs/c.1

# activate new config
echo "" > UDC
echo "ff300000.usb" > UDC