mirror of https://gitee.com/openkylin/linux.git
4f6676274f
Simplify processing of completed qtds, and correct handling of short reads, by removing two state variables: - "qtd_status" wasn't needed. The current URB's status is either OK (-EINPROGRESS) or some fault status. Once a fault appears, the queue halts and any later QTDs are immediately removed, so no temporary status is needed. (Or for typical short reads, it's not treated as a fault, so no queue halt is needed.) - "do_status" was erroneous. Because of how the queue is set up, short control reads can (and should!) be treated like full size reads, and cleaned up the usual way. The status stage will be executed transparently, and usbcore handles the choice of whether to report this status as unexected. The "do_status" problem caused a rather perplexing timing-dependent problem with usbtest case 10. Sometimes it would make the controller skip a dozen transactions while (wrongly) trying to clean up after a short transfer. Fortunately, removing a dcache contention issue made this become trivial to reproduce (on one test rig), so enough clues finally presented themselves ... I think this has been around for a very long time, but was worsened by recent urb->status changes. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
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| class | ||
| core | ||
| gadget | ||
| host | ||
| image | ||
| misc | ||
| mon | ||
| serial | ||
| storage | ||
| Kconfig | ||
| Makefile | ||
| README | ||
| usb-skeleton.c | ||
README
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.