1 usb_composition命令
# cat /sbin/usb/target
# cd /sys/class/android_usb/android0
# cat functions
console shows that QCOM’s default configuration
Usage: usb_composition [Pid] [HSIC] [PERSISTENT] [IMMEDIATE] [FROM_ADBD]
usb_composition 9025 n y y
Then this script will call
/sbin/usb/compositions/$pid n 0.2 $from_adb
ARG1: means path of /sys/class/android_usb/androidX, X = 0 if ARG1 is‘n’
ARG2: delay seconds, for example, sleep 0.2
ARG3: firstly kill adbd and then start adbd when ARG3 is‘n’
2 源代码和编译后的命令路径
USB slave:
system/core/usb/start_usb ---> /etc/rcS.d/S30usb
system/core/usb/usb_composition ---> /sbin/usb_composition
system/core/usb/compositions ---> /sbin/usb/compositions
/sbin/usb/compositions/$PID ---> /sbin/usb/boot_hsusb_composition
adbd:
system/core/adb/start_adbd ---> /etc/init.d/adbd
system/core/adb/adbd ---> /sbin/adbd
bitbake file: oe-core/meta-msm/recipes/system-core/system-core_git.bb
3 Abbreviations
ARC：Argonant RISC Core
AT91SAM9260：SAM means Smart ARM-based Microcontroller
ATMEL SAMBA：ATMEL Smart ARM-based Microcontroller Boot Assistant
CC2530：TI ChipCon2530
DWC2：Design Ware Controller 2，Apple的嵌入式设备，包括iPad和iPhone都是使用的DWC2
ISP1161：Philips' Integrated host Solution Pairs 1161，“Firms introduce USB host controllers”，https://www.eetimes.com/document.asp?doc_id=1290054
Quirks: The Attributes of Device A Considered that are expected to Operation BE noncompliant with
SL811HS: Cypress / ScanLogic the Host 811 / the Slave, the performance and ISP1161 (Integrated host Solution Pairs 1161) rather
TDI: TransDimension Inc., a company that invented the first TT integrated into the method EHCI RootHub in, so for embedded systems, eliminating the need for OHCI / UHCI hardware, while reducing costs, as a memorial to the company, Linux kernel defines a macro ehci_is_TDI (ehci); product UHC124 expressed USB Host controller; the acquisition of ARC USB technology; now owned by chipidea, chipidea mips has been acquired
TLV: TI Low Value, cost-effective
TPS: TI Performance Solution
TT: transaction Translator (transaction converter, USB2.0 of USB1.1 packet into the package)
