dwc2 (on Meson8b) doesn't detect "hot-plugged" USB devices

[Martin Blumenstingl]

Hello,

I was a bit surprised to see that hot-plugging USB devices on Amlogic
Meson8b (for example: Odroid-C1) is broken.
to be fair: I *think* it worked before, but I cannot guarantee it nor
can I say when it broke

all examples below are from an Odroid-C1 board with Amlogic Meson8b (S805) SoC.
this connects a (fixed, soldered down) 4-port USB hub to the dwc2
controller (which is in "host" mode)

during boot I see:
[    1.651687] dwc2 c90c0000.usb: c90c0000.usb supply vusb_d not
found, using dummy regulator
[    1.654434] dwc2 c90c0000.usb: c90c0000.usb supply vusb_a not
found, using dummy regulator
[    1.732374] dwc2 c90c0000.usb: dwc2_check_params: Invalid parameter lpm=1
[    1.733526] dwc2 c90c0000.usb: dwc2_check_params: Invalid parameter
lpm_clock_gating=1
[    1.741427] dwc2 c90c0000.usb: dwc2_check_params: Invalid parameter besl=1
[    1.748305] dwc2 c90c0000.usb: dwc2_check_params: Invalid parameter
hird_threshold_en=1
[    1.756491] dwc2 c90c0000.usb: DWC OTG Controller
[    1.760993] dwc2 c90c0000.usb: new USB bus registered, assigned bus number 1
[    1.768046] dwc2 c90c0000.usb: irq 24, io mem 0xc90c0000
[    1.773947] hub 1-0:1.0: USB hub found
[    1.777063] hub 1-0:1.0: 1 port detected
...
[    2.212432] usb 1-1: new high-speed USB device number 2 using dwc2
[    2.464742] hub 1-1:1.0: USB hub found
[    2.465118] hub 1-1:1.0: 4 ports detected

if a USB device is plugged into one of the four USB ports during boot
then it is detected automatically.
if I plug in devices later they are not detected automatically (I have
to run "lsusb -v" due to some reason, then hot-plugged devices are
being detected)
un-plugging USB devices is recognized instantly (no "lsusb" trickery
is required)

is this a known issue? how can I help debugging?
any help is appreciated!

below is the output of all dwc2 debugfs files.


Regards
Martin


[rootodroidc1 c90c0000.usb]# cat dr_mode
host
[rootodroidc1 c90c0000.usb]# cat fifo
Non-periodic FIFOs:
RXFIFO: Size 0
NPTXFIFO: Size 0, Start 0x00000000

Periodic TXFIFOs:
[rootodroidc1 c90c0000.usb]# cat hw_params
op_mode                       : 5
arch                          : 2
dma_desc_enable               : 1
enable_dynamic_fifo           : 1
en_multiple_tx_fifo           : 0
rx_fifo_size                  : 2048
host_nperio_tx_fifo_size      : 2048
dev_nperio_tx_fifo_size       : 0
host_perio_tx_fifo_size       : 2048
nperio_tx_q_depth             : 4
host_perio_tx_q_depth         : 4
dev_token_q_depth             : 8
max_transfer_size             : 524287
max_packet_count              : 1023
host_channels                 : 16
hs_phy_type                   : 1
fs_phy_type                   : 0
i2c_enable                    : 0
num_dev_ep                    : 2
num_dev_perio_in_ep           : 0
total_fifo_size               : 1984
power_optimized               : 1
utmi_phy_data_width           : 1
snpsid                        : 0x4f54310a
dev_ep_dirs                   : 0x0
[rootodroidc1 c90c0000.usb]# cat params
otg_cap                       : 2
dma_desc_enable               : 0
dma_desc_fs_enable            : 0
speed                         : 0
enable_dynamic_fifo           : 1
en_multiple_tx_fifo           : 0
host_rx_fifo_size             : 512
host_nperio_tx_fifo_size      : 500
host_perio_tx_fifo_size       : 500
max_transfer_size             : 524287
max_packet_count              : 1023
host_channels                 : 16
phy_type                      : 1
phy_utmi_width                : 16
phy_ulpi_ddr                  : 0
phy_ulpi_ext_vbus             : 0
i2c_enable                    : 0
ulpi_fs_ls                    : 0
host_support_fs_ls_low_power  : 0
host_ls_low_power_phy_clk     : 0
ts_dline                      : 0
reload_ctl                    : 1
ahbcfg                        : 0xa
uframe_sched                  : 0
external_id_pin_ctl           : 0
power_down                    : 1
lpm                           : 0
lpm_clock_gating              : 0
besl                          : 0
hird_threshold_en             : 0
hird_threshold                : 4
host_dma                      : 1
g_dma                         : 0
g_dma_desc                    : 0
g_rx_fifo_size                : 0
g_np_tx_fifo_size             : 0
g_tx_fifo_size[0]             : 0
g_tx_fifo_size[1]             : 0
g_tx_fifo_size[2]             : 0
g_tx_fifo_size[3]             : 0
g_tx_fifo_size[4]             : 0
g_tx_fifo_size[5]             : 0
g_tx_fifo_size[6]             : 0
g_tx_fifo_size[7]             : 0
g_tx_fifo_size[8]             : 0
g_tx_fifo_size[9]             : 0
g_tx_fifo_size[10]            : 0
g_tx_fifo_size[11]            : 0
g_tx_fifo_size[12]            : 0
g_tx_fifo_size[13]            : 0
g_tx_fifo_size[14]            : 0
g_tx_fifo_size[15]            : 0
[rootodroidc1 c90c0000.usb]# cat state
DCFG=0x00000000, DCTL=0x00000000, DSTS=0x00000000
DIEPMSK=0x00000000, DOEPMASK=0x00000000
GINTMSK=0xf0000000, GINTSTS=0x00000001
DAINTMSK=0x00000000, DAINT=0x00000000
GNPTXSTS=0x00000000, GRXSTSR=00000000

Endpoint status:
[rootodroidc1 c90c0000.usb]# cat testmode
no test
[rootodroidc1 c90c0000.usb]# cat regdump
<system hangs>