Testing has happened with Acer Travelmate 332T featuring USB OHCI and
linux kernel 2.2.21. The driver also compiles and runs with 2.4.18 with
the same hadware. Also UHCI desktop system with 2.4.x kernel has been tested.

BUGS
----
! Programs like camsource open the device and leave it open even if grabbing
  images only now and then. The driver streams all the time, should stop
  streaming if images are not captured even if device is still open.
- Changing the exposure with HDCS sensor causes corrupted frames. Especially
  bad with automatic exposure control.
- There are corrupted frames now and then, at least with VV6410.
- Sometimes the image sequence doesn't start. You need to restart your
  camera software many times, it will then start eventually. Reason unknown.
- Sometimes (rarely) I get message
	already running port 1 disabled by hub (EMI?), re-enabling...
  from Linux and the driver must be reloaded before the camera works again.
  Not a problem in this driver (but probably in kernel drivers or in hardware),
  I believe. Caused by power overload? Currently the driver tries to work
  around this problem, but the workaround doesn't always work with VV6410.
  This seems to happen only on OHCI laptop, not on UHCI desktop.
- My computer seems to hang if I physically unplug the camera while drivers
  are still loaded. To be investigated...
  This might be a problem with 2.2.x only.
  Not a problem in this driver (but probably in kernel drivers), I believe.
! subsample=1 doesn't subsample vertically with Photobit and doesn't
  work at all with VV6410.
- QuickCam Web (0x046D/0x0870) doesn't work with any other camera (UHCI).
  Seems to be problem with hardware/Linux USB drivers. Reqs too much power?
  Happens even in different root hubs. Works on other computers.
- When QuickCam Web is unplugged and replugged while the camera is in use,
  the video stream doesn't restart with kernel 2.6.0. Works with other cameras,
  works with all cameras in 2.4.x. This one makes no sense.
  Hmm... not sure if kernel version matters, happens sometimes with 2.4.x too.
  Hmm... works now fine with 2.6.7.
- When using simultaneously two cameras in different busses under 2.6.x
  and killing the applications suddenly (like killall -9 xawtv) there's
  about 1/3 possibility for total kernel crash. Even SysRq doesn't work.
  No panic/oops messages, rarely I get messages of recursive call to do_irq
  and stack overflow. (Nforce2-OHCI)
  Hmm... can't reproduce anymore with 2.6.7.
- Older versions of the driver worked (qce-ga) but the new versions don't.
  This might be problem mainly with VV6410 sensor and ProductId=850.
  USER_OPT=-DQCEGA_MODE=1 sometimes seems to help but not always.
- Non-ASCII characters turn into "?"-characters in /proc/version confusing
  quickcam.sh.

(!=can be fixed with current knowledge, needs just doing it)

TODO
----
- Allow changing driver options with qcset while another application has the
  driver open. Problem: second open("/dev/video") fails. Why? Using procfs
  would solve this. Works with 2.6.x.
- Automatic gain control is less sophisticated and accurate than the exposure
  control. Gain also decreases image quality, sometimes very much. So please
  try to use enough light that gain can be kept at minimum.
- Look what we need to make sound and button working with QuickCam Web.
- Make compression to other supported cameras as well.
- Better bayer-to-RGB conversions. IIR filter, edge detection, template
  matching, speculative pixel selection... (hi Cagdas!)
- Allow using software exposure control with Photobit (if it's better)
  It appears that the Photobit internal autoexposure changes exposure by
  a constant value, and on very small integration times (much light)
  it is simply too rough and can not find a good integration time.
  This leads either to dirty gray image or oscillation (if R17 is too small).
- Allow using multiple cameras on same bus (lower bandwidth,
  is it possible? Maybe not with all camera).
- Implement sensor defect correction.
- Allow setting hue on Photobit even with automatic exposure control.
- Flicker avoidance (exposure time should be multiple of 50/60 Hz)
- Add support for dkms
- Add Gstreamer module to handle format conversions, possibly with vloopback
- Add option to allow very long exposure times (with at least HDCS).
- Add accumulation mode support for HDCS sensor
- quickcam.sh should look for necessary drivers (USB, video) from
  /proc/ksyms, not if the modules have been loaded, because the latter
  doesn't work when modules have been compiled statically.
- Multiple opens don't work very well. Should improve.

DONE
----
! Photobit brightness control doesn't seem to work very well.
- When buffers are full, the oldest frame should be dropped (not newest).
  This still doesn't work if the buffers get full while read()
  or ioctl() calls are being done (or more accurately, when driver is
  running in function qc_capt_get(), but with two buffers it can't be
  made better. With three buffers it could be done, but is it worthwhile?