6193d6997c
In case one "forgot" to load the receiver i.e. doing
|modprobe omap2430
|modprobe musb_hdrc
he ends up with:
|musb-hdrc: version 6.0, ?dma?, otg (peripheral+host)
|HS USB OTG: no transceiver configured
|musb-hdrc musb-hdrc: musb_init_controller failed with status -19
|(NULL device *): gadget not registered.
|Unable to handle kernel NULL pointer dereference at virtual address 0000001c
|Internal error: Oops: 17 [#1] SMP
|[<c011383c>] (sysfs_find_dirent+0x4/0x60) from [<c01138c0>] (sysfs_get_dirent+0x28/0x78)
|[<c01138c0>] (sysfs_get_dirent+0x28/0x78) from [<c0115b78>] (sysfs_unmerge_group+0x1c/0x90)
|[<c0115b78>] (sysfs_unmerge_group+0x1c/0x90) from [<c0179ba4>] (dpm_sysfs_remove+0x14/0x3c)
|[<c0179ba4>] (dpm_sysfs_remove+0x14/0x3c) from [<c01742f8>] (device_del+0x40/0x1b4)
|[<c01742f8>] (device_del+0x40/0x1b4) from [<c0174478>] (device_unregister+0xc/0x18)
|[<c0174478>] (device_unregister+0xc/0x18) from [<bf0489b4>] (musb_free+0x24/0x88 [musb_hdrc])
|[<bf0489b4>] (musb_free+0x24/0x88 [musb_hdrc]) from [<bf057d18>] (musb_probe+0xb50/0xe3c [musb_hdrc])
|[<bf057d18>] (musb_probe+0xb50/0xe3c [musb_hdrc]) from [<c01779c4>] (platform_drv_probe+0x1c/0x24)
The problem is that musb_free() tries to figure out what was
initializued and what wasn't and clean up only the initialized part.
This works well for usb_del_gadget_udc() but device_unregister() can't
deal with it. Therefore we rely on the fact the we always have a parent
device and only then remove the device.
I broke this in
|
||
---|---|---|
.. | ||
atm | ||
c67x00 | ||
class | ||
core | ||
early | ||
gadget | ||
host | ||
image | ||
misc | ||
mon | ||
musb | ||
otg | ||
renesas_usbhs | ||
serial | ||
storage | ||
wusbcore | ||
Kconfig | ||
Makefile | ||
README | ||
usb-skeleton.c |
To understand all the Linux-USB framework, you'll use these resources: * This source code. This is necessarily an evolving work, and includes kerneldoc that should help you get a current overview. ("make pdfdocs", and then look at "usb.pdf" for host side and "gadget.pdf" for peripheral side.) Also, Documentation/usb has more information. * The USB 2.0 specification (from www.usb.org), with supplements such as those for USB OTG and the various device classes. The USB specification has a good overview chapter, and USB peripherals conform to the widely known "Chapter 9". * Chip specifications for USB controllers. Examples include host controllers (on PCs, servers, and more); peripheral controllers (in devices with Linux firmware, like printers or cell phones); and hard-wired peripherals like Ethernet adapters. * Specifications for other protocols implemented by USB peripheral functions. Some are vendor-specific; others are vendor-neutral but just standardized outside of the www.usb.org team. Here is a list of what each subdirectory here is, and what is contained in them. core/ - This is for the core USB host code, including the usbfs files and the hub class driver ("khubd"). host/ - This is for USB host controller drivers. This includes UHCI, OHCI, EHCI, and others that might be used with more specialized "embedded" systems. gadget/ - This is for USB peripheral controller drivers and the various gadget drivers which talk to them. Individual USB driver directories. A new driver should be added to the first subdirectory in the list below that it fits into. image/ - This is for still image drivers, like scanners or digital cameras. ../input/ - This is for any driver that uses the input subsystem, like keyboard, mice, touchscreens, tablets, etc. ../media/ - This is for multimedia drivers, like video cameras, radios, and any other drivers that talk to the v4l subsystem. ../net/ - This is for network drivers. serial/ - This is for USB to serial drivers. storage/ - This is for USB mass-storage drivers. class/ - This is for all USB device drivers that do not fit into any of the above categories, and work for a range of USB Class specified devices. misc/ - This is for all USB device drivers that do not fit into any of the above categories.