Android USB OTG converted to host debug note

(Original works, reproduced please indicate the path of reprint)

Recently on the MStar 786 platform, there is a need, that is, the USB OTG converted to a host USB drive.

Start debugging, thought as long as the OTG configuration removed, that is, CONFIG_USB_MS_OTG shield off, but after compiling the burn, insert and dial out the USB flash drive when found prompt

Android_work:did not send uevent (0 0 (NULL))

The flash drive does not light up, indicating that there is no power on.

Later search for information, only to find the need to pull the usb_cid foot low, low to show work in the host mode.

There are 2 ways to pull the pin down:

1) force it to pull down on the hardware.

2) pull down the software, in the kernel directory of the DRIVERS\USB\OTG\MS_OTG.C in the MS_OTG_INIT_IRQ function, the following code to screen off:

OTG ID pin pull-up
/* reg_t = READL (&msotg->op_regs->usbc_regs->port_ctrl);
reg_t |= Idpullup_ctrl;
Writel (reg_t, &msotg->op_regs->usbc_regs->port_ctrl); * *

After compiling the burn, the boot is inserted into the USB flash drive, with the following log, indicating successful recognition:

[1374.141871] Hub_events


[1374.144655] Hub_port_connect_change


[1374.303911] Hub_port_init


[1374.306911] ==13==> hub_port_init 1
[1374.310873] Plug in USB Port1
[1374.503906] USB 3-1: New high Speed USB device number 3 using Mstar-ehci-1
[1374.958064] usb-storage 3-1:1.0:quirks match for vid 058f pid 6,387:20
[1374.965494] usb-storage 3-1:1.0:this device (058f,6387,010b S) have unneeded subclass and Protocol entries in U Nusual_devs.h (Kernel 3.4.5)
[1374.965505] Please send a copy of the message to <[email protected]> and <[email protected]>
[1374.992704] Scsi1:usb-storage 3-1:1.0
[1374.999392] Hub_events


[1375.002158] Hub_events


[1375.996046] SCSI 1:0:0:0: direct-access Generic Flash Disk 8.07 pq:0 ansi:4
[1376.008295] SD 1:0:0:0: [SDB] 16293888 512-byte logical blocks: (8.34 gb/7.76 GiB)
[1376.017568] SD 1:0:0:0: [SDB] Write Protect is off
[1376.023685] SD 1:0:0:0: [SDB] Write cache:disabled, read cache:enabled, doesn ' t support DPO or FUA
[1376.038784] Sdb:sdb1
[1376.046711] SD 1:0:0:0: [SDB] attached SCSI removable disk
[1376.054754] SD 1:0:0:0: attached SCSI generic sg0 type 0

After recognition succeeds, a device node is generated under/dev/block/, possibly called sda1

You need to mount it manually to the MNT directory before you can access it:

Mount-t Vfat/dev/block/sda1/mnt/sdcard

You can then access the contents of the USB flash drive under root privileges on CD SDcard

Android USB OTG converted to host debug note