CP2105 dual uart in one USB

http://community.silabs.com/t5/Interface/CP2105-driver-questions/td-p/89191

不用hub 哦，有linux driver.

kmesg

[20172.062093] usb 3-1.1: new full-speed USB device number 4 using xhci_hcd
[20172.164457] usb 3-1.1: New USB device found, idVendor=10c4, idProduct=ea70
[20172.164464] usb 3-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=5
[20172.164468] usb 3-1.1: Product: CP2105 Dual USB to UART Bridge Controller
[20172.164470] usb 3-1.1: Manufacturer: Silicon Labs
[20172.164473] usb 3-1.1: SerialNumber: 00775A41
[20172.232931] usbcore: registered new interface driver usbserial
[20172.232971] usbcore: registered new interface driver usbserial_generic
[20172.233003] usbserial: USB Serial support registered for generic
[20172.258589] usbcore: registered new interface driver cp210x
[20172.258646] usbserial: USB Serial support registered for cp210x
[20172.258718] cp210x 3-1.1:1.0: cp210x converter detected
[20172.342494] usb 3-1.1: reset full-speed USB device number 4 using xhci_hcd
[20172.443147] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8801bd4d3d48
[20172.443155] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8801bd4d3d00
[20172.443158] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8801bd4d35c8
[20172.443160] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8801bd4d3580
[20172.443879] usb 3-1.1: cp210x converter now attached to ttyUSB0
[20172.443955] cp210x 3-1.1:1.1: cp210x converter detected
[20172.444112] cp210x ttyUSB0: cp210x converter now disconnected from ttyUSB0
[20172.444145] cp210x 3-1.1:1.0: device disconnected
[20172.526619] usb 3-1.1: reset full-speed USB device number 4 using xhci_hcd
[20172.627173] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8801bd4d3d48
[20172.627182] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8801bd4d3d00
[20172.627185] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8801bd4d35c8
[20172.627188] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8801bd4d3580
[20172.627595] cp210x 3-1.1:1.0: cp210x converter detected
[20172.710760] usb 3-1.1: reset full-speed USB device number 4 using xhci_hcd
[20172.811375] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8801bd4d3d48
[20172.811383] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8801bd4d3d00
[20172.811387] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8801bd4d35c8
[20172.811390] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8801bd4d3580
[20172.812071] usb 3-1.1: cp210x converter now attached to ttyUSB0
[20172.812417] usb 3-1.1: cp210x converter now attached to ttyUSB1
[20172.838229] cp210x ttyUSB1: failed to set baud rate to 300

cp2105 的datasheet
有兩個 port: enhanced, standard

Enhanced UART Interface Features

Data formats supported:
- Data bits: 5, 6, 7, and 8
- Stop bits: 1, 1.5, and 2
- Parity: odd, even, mark, space, no parity
Baud rates: 300 bps to 2.0 Mbps
320 Byte receive and transmit buffers
Two GPIO signals for status and control
RS-485 mode with bus transceiver control

Standard UART Interface Features

Data format: 8 data bits, 1 Stop bit
Parity: Even, Odd, No parity
Baud rates: 2400 bps to 921600 bps
288 Byte receive and transmit buffers
Three GPIO signals for status and control

果然enhanced 比較快，也可以必較慢。
-- 但是 ti 的 evb 卻選 standard port 為 data port....