linux/drivers/usb
Dan Williams 12f188f2e5 ueagle-atm: fix PHY signal initialization race
A race exists when initializing ueagle-atm devices where the generic atm
device may not yet be created before the driver attempts to initialize
it's PHY signal state, which checks whether the atm device has been
created or not.  This often causes the sysfs 'carrier' attribute to be
'1' even though no signal has actually been found.

uea_probe
   usbatm_usb_probe
      driver->bind (uea_bind)
         uea_boot
            kthread_run(uea_kthread)     uea_kthread
      usbatm_atm_init                       uea_start_reset
         atm_dev_register                      UPDATE_ATM_SIGNAL

UPDATE_ATM_SIGNAL checks whether the ATM device has been created and if
not, will not update the PHY signal state.  Because of the race that
does not always happen in time, and the PHY signal state remains
ATM_PHY_SIG_FOUND even though no signal exists.

To fix the race, just create the kthread during initialization, and only
after initialization is complete, start the thread that reboots the
device and initializes PHY state.

[ 3030.490931] uea_probe: calling usbatm_usb_probe
[ 3030.490946] ueagle-atm 8-2:1.0: usbatm_usb_probe: trying driver ueagle-atm with vendor=1110, product=9031, ifnum  0
[ 3030.493691] uea_bind: setting usbatm
[ 3030.496932] usb 8-2: [ueagle-atm] using iso mode
[ 3030.497283] ueagle-atm 8-2:1.0: usbatm_usb_probe: using 3021 byte buffer for rx channel 0xffff880125953508
   <kthread already started before usbatm_usb_probe() has returned>
[ 3030.497292] usb 8-2: [ueagle-atm] (re)booting started
   <UPDATE_ATM_SIGNAL checks whether ATM device has been created yet before setting PHY state>
[ 3030.497298] uea_start_reset: atm dev (null)
   <and since it hasn't been created yet PHY state is not set>
[ 3030.497306] ueagle-atm 8-2:1.0: usbatm_usb_probe: using 3392 byte buffer for tx channel 0xffff8801259535b8
[ 3030.497374] usbatm_usb_probe: about to init
[ 3030.497379] usbatm_usb_probe: calling usbatm_atm_init
   <atm device finally gets created>
[ 3030.497384] usbatm_atm_init: creating atm device!

Signed-off-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-12-28 13:41:41 -08:00
..
atm ueagle-atm: fix PHY signal initialization race 2010-12-28 13:41:41 -08:00
c67x00 usb: makefile cleanup 2010-10-22 10:22:07 -07:00
class Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6 2010-10-22 20:30:48 -07:00
core USB: core: Add input prompt and help text for USB_OTG config 2010-12-16 15:45:44 -08:00
early usb: makefile cleanup 2010-10-22 10:22:07 -07:00
gadget Revert "USB: gadget: Allow function access to device ID data during bind()" 2010-12-16 15:52:30 -08:00
host xhci: Fix issue with port array setup and buggy hosts. 2010-12-09 11:59:42 -08:00
image SCSI host lock push-down 2010-11-16 13:33:23 -08:00
misc USB: misc: uss720.c: add another vendor/product ID 2010-12-16 15:45:45 -08:00
mon BKL: remove extraneous #include <smp_lock.h> 2010-11-17 08:59:32 -08:00
musb usb: musb: do not use dma for control transfers 2010-11-22 12:55:02 +02:00
otg USB: OTG: langwell_otg: fix up some sysfs attribute permissions 2010-11-15 14:04:15 -08:00
serial USB: ftdi_sio: Add D.O.Tec PID 2010-12-10 13:01:52 -08:00
storage USB: usb-storage: unusual_devs entry for the Samsung YP-CP3 2010-12-16 15:45:45 -08:00
wusbcore usb: makefile cleanup 2010-10-22 10:22:07 -07:00
Kconfig USB: add USB EHCI support for MPC5121 SoC 2010-10-22 10:21:58 -07:00
Makefile USB: drivers/usb/Makefile: conditionally descend to 'early' 2010-08-10 14:35:38 -07:00
README
usb-skeleton.c llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00

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.