docking bar limits charging rate?

[8bit]

Are you using a PD capable charger? With a PD charger (from a Pixel, capable of 3A at 5V) I get the same 1500mA with or without the dock. 

Code:

cat /sys/class/power_supply/axp20x-usb/uevent
POWER_SUPPLY_NAME=axp20x-usb
POWER_SUPPLY_TYPE=USB
POWER_SUPPLY_HEALTH=Good
POWER_SUPPLY_PRESENT=1
POWER_SUPPLY_ONLINE=1
POWER_SUPPLY_VOLTAGE_MIN=4500000
POWER_SUPPLY_INPUT_CURRENT_LIMIT=3000000
POWER_SUPPLY_USB_BC_ENABLED=0
POWER_SUPPLY_USB_DCP_INPUT_CURRENT_LIMIT=1500000
POWER_SUPPLY_USB_TYPE=[PD] SDP DCP CDP Unknown

The device has to negotiate with the PD power supply, since with the dock the phone may be either powered by the dock or provide power to it. You can see it in dmesg.

Code:

[28898.854286] anx7688 1-0028: plug irq (cd=1)
[28898.872420] anx7688 1-0028: cable inserted
[28898.912415] anx7688 1-0028: power enabled
[28898.976557] anx7688 1-0028: eeprom0 = 0x03
[28898.976592] anx7688 1-0028: fw loaded after 40 ms
[28898.976778] anx7688 1-0028: OCM firmware loaded (version 0x2410)
[28898.977797] anx7688 1-0028: send pd packet cmd=0x00 05 00 32 90 01 26 12
[28899.025671] anx7688 1-0028: send pd packet cmd=0x01 05 01 2c 91 01 26 16
[28899.026265] anx7688 1-0028: send pd packet cmd=0x02 11 02 00 00 00 ec 00 00 00 00 00 00 00 00 39 00 00 51 77
[28899.027117] anx7688 1-0028: send pd packet cmd=0x03 05 03 00 00 01 ff f8
[28899.027658] anx7688 1-0028: OCM configuration completed
[28899.028624] anx7688 1-0028: status changed to 0x00
[28899.028658] anx7688 1-0028: cc_status changed to CC1 = SRC.Open CC2 = SRC.Open
[28899.028687] anx7688 1-0028: DP state changed to 0x00
[28899.028702] anx7688 1-0028: VCONN role change to SINK
[28899.028738] anx7688 1-0028: DATA role change requested to UFP
[28899.469100] anx7688 1-0028: cc_status changed to CC1 = SRC.Open CC2 = SNK.Power3.0
[28899.543177] anx7688 1-0028: recv ocm message cmd=0x00 09 00 2c 91 01 08 c8 d0 02 00 97
[28899.543248] anx7688 1-0028: received SRC_CAP
[28899.543259] anx7688 1-0028: SRC_CAP PDO_FIXED (5000mV 3000mA)
[28899.543275] anx7688 1-0028: SRC_CAP PDO_FIXED (9000mV 2000mA)
[28899.543560] anx7688 1-0028: RDO max voltage = 5000mV, max power = 15000mW, PD current limit = 3000mA
[28899.547075] anx7688 1-0028: recv ocm message cmd=0xf0 03 f0 16 00 f7
[28899.547119] anx7688 1-0028: received response to PWR_OBJ_REQ (SUCCESS)
[28900.828878] anx7688 1-0028: updating power mode to PD, current limit 3000mA (0 => BC1.2)
[28900.828942] anx7688 1-0028: disabling USB BC 1.2 detection
[28900.829038] anx7688 1-0028: setting vbus_in current limit to 3000 mA
[28900.829125] anx7688 1-0028: enabling vbus_in power path