linux/drivers/usb
Hans Verkuil f1e393de38 [media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of just per-fh
The driver had to decide how many events to allocate when the v4l2_fh struct
was created. It was possible to add more events afterwards, but there was no
way to ensure that you wouldn't miss important events if the event queue
would fill up for that filehandle.

In addition, once there were no more free events, any new events were simply
dropped on the floor.

For the control event in particular this made life very difficult since
control status/value changes could just be missed if the number of allocated
events and the speed at which the application read events was too low to keep
up with the number of generated events. The application would have no idea
what the latest state was for a control since it could have missed the latest
control change.

So this patch makes some major changes in how events are allocated. Instead
of allocating events per-filehandle they are now allocated when subscribing an
event. So for that particular event type N events (determined by the driver)
are allocated. Those events are reserved for that particular event type.
This ensures that you will not miss events for a particular type altogether.

In addition, if there are N events in use and a new event is raised, then
the oldest event is dropped and the new one is added. So the latest event
is always available.

This can be further improved by adding the ability to merge the state of
two events together, ensuring that no data is lost at all. This will be
added in the next patch.

This also makes it possible to allow the user to determine the number of
events that will be allocated. This is not implemented at the moment, but
would be trivial.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:53:31 -03:00
..
atm Fix common misspellings 2011-03-31 11:26:23 -03:00
c67x00 Fix common misspellings 2011-03-31 11:26:23 -03:00
class USB: cdc-acm: Adding second ACM channel support for Nokia E7 and C7 2011-06-06 15:59:41 -07:00
core USB: additional regression fix for device removal 2011-07-07 13:29:33 -07:00
early USB: EHCI: Support controllers with big endian capability regs 2011-05-03 11:43:21 -07:00
gadget [media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of just per-fh 2011-07-27 17:53:31 -03:00
host usb: r8a66597-hcd: fix cannot detect low/full speed device 2011-06-27 13:46:44 -07:00
image Fix common misspellings 2011-03-31 11:26:23 -03:00
misc Merge branch 'usb-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6 2011-05-23 12:33:02 -07:00
mon USB: usbmon: fix-up docs and text API for sparse ISO 2011-02-04 11:46:57 -08:00
musb usb: musb: gadget: clear TXPKTRDY flag when set FLUSHFIFO 2011-06-09 12:01:03 +03:00
otg USB: TWL6025 allow different regulator name 2011-05-27 10:49:30 +01:00
renesas_usbhs usb/renesas_usbhs: free uep on removal 2011-06-06 16:28:04 -07:00
serial USB: Add new FT232H chip to drivers/usb/serial/ftdi_sio.c 2011-06-27 13:46:44 -07:00
storage usb-storage: redo incorrect reads 2011-06-07 09:05:42 -07:00
wusbcore Fix common misspellings 2011-03-31 11:26:23 -03:00
Kconfig USB: EHCI: Add bus glue for GRLIB GRUSBHC controller 2011-05-03 11:43:48 -07:00
Makefile USB: fix build of FSL MPH DR OF platform driver 2011-05-02 16:59:37 -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.