6d88e67925
This patch (as1390) fixes a problem that crops up when a UHCI host controller is unbound from uhci-hcd while there are still some active URBs. The URBs have to be unlinked when the root hub is unregistered, and uhci-hcd relies upon root-hub status polls as part of its unlinking procedure. But usb_hcd_poll_rh_status() won't make those status calls if hcd->rh_registered is clear, and the flag is cleared _before_ the unregistration takes place. Since hcd->rh_registered is used for other things and needs to be cleared early, the solution is to add a new flag (rh_pollable) and use it instead. It gets cleared _after_ the root hub is unregistered. Now that the status polls don't end too soon, we have to make sure they also don't occur too late -- after the root hub's usb_device structure or the HCD's private structures are deallocated. Therefore the patch adds usb_get_device() and usb_put_device() calls to protect the root hub structure, and it adds an extra del_timer_sync() to prevent the root-hub timer from causing an unexpected status poll. This additional complexity would not be needed if the HCD framework had provided separate stop() and release() callbacks instead of just stop(). This lack could be fixed at some future time (although it would require changes to every host controller driver); when that happens this patch won't be needed any more. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
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atm | ||
c67x00 | ||
class | ||
core | ||
early | ||
gadget | ||
host | ||
image | ||
misc | ||
mon | ||
musb | ||
otg | ||
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.