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android_kernel_xiaomi_sm8350/Documentation/video4linux/w9968cf.txt
Michael Krufky 6e20409004 V4L/DVB (4042): Documentation: whitespace cleanup 
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
2006-06-25 02:00:38 -03:00

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W996[87]CF JPEG USB Dual Mode Camera Chip
Driver for Linux 2.6 (basic version)
=========================================
- Documentation -
Index
=====
1. Copyright
2. Disclaimer
3. License
4. Overview
5. Supported devices
6. Module dependencies
7. Module loading
8. Module paramaters
9. Contact information
10. Credits
1. Copyright
============
Copyright (C) 2002-2004 by Luca Risolia <luca.risolia@studio.unibo.it>
2. Disclaimer
=============
Winbond is a trademark of Winbond Electronics Corporation.
This software is not sponsored or developed by Winbond.
3. License
==========
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
4. Overview
===========
This driver supports the video streaming capabilities of the devices mounting
Winbond W9967CF and Winbond W9968CF JPEG USB Dual Mode Camera Chips. OV681
based cameras should be supported as well.
The driver is divided into two modules: the basic one, "w9968cf", is needed for
the supported devices to work; the second one, "w9968cf-vpp", is an optional
module, which provides some useful video post-processing functions like video
decoding, up-scaling and colour conversions.
Note that the official kernels do neither include nor support the second
module for performance purposes. Therefore, it is always recommended to
download and install the latest and complete release of the driver,
replacing the existing one, if present.
The latest and full-featured version of the W996[87]CF driver can be found at:
http://www.linux-projects.org. Please refer to the documentation included in
that package, if you are going to use it.
Up to 32 cameras can be handled at the same time. They can be connected and
disconnected from the host many times without turning off the computer, if
your system supports the hotplug facility.
To change the default settings for each camera, many parameters can be passed
through command line when the module is loaded into memory.
The driver relies on the Video4Linux, USB and I2C core modules. It has been
designed to run properly on SMP systems as well. An additional module,
"ovcamchip", is mandatory; it provides support for some OmniVision image
sensors connected to the W996[87]CF chips; if found in the system, the module
will be automatically loaded by default (provided that the kernel has been
compiled with the automatic module loading option).
5. Supported devices
====================
At the moment, known W996[87]CF and OV681 based devices are:
- Aroma Digi Pen VGA Dual Mode ADG-5000 (unknown image sensor)
- AVerMedia AVerTV USB (SAA7111A, Philips FI1216Mk2 tuner, PT2313L audio chip)
- Creative Labs Video Blaster WebCam Go (OmniVision OV7610 sensor)
- Creative Labs Video Blaster WebCam Go Plus (OmniVision OV7620 sensor)
- Lebon LDC-035A (unknown image sensor)
- Ezonics EZ-802 EZMega Cam (OmniVision OV8610C sensor)
- OmniVision OV8610-EDE (OmniVision OV8610 sensor)
- OPCOM Digi Pen VGA Dual Mode Pen Camera (unknown image sensor)
- Pretec Digi Pen-II (OmniVision OV7620 sensor)
- Pretec DigiPen-480 (OmniVision OV8610 sensor)
If you know any other W996[87]CF or OV681 based cameras, please contact me.
The list above does not imply that all those devices work with this driver: up
until now only webcams that have an image sensor supported by the "ovcamchip"
module work. Kernel messages will always tell you whether this is case.
Possible external microcontrollers of those webcams are not supported: this
means that still images cannot be downloaded from the device memory.
Furthermore, it's worth to note that I was only able to run tests on my
"Creative Labs Video Blaster WebCam Go". Donations of other models, for
additional testing and full support, would be much appreciated.
6. Module dependencies
======================
For it to work properly, the driver needs kernel support for Video4Linux, USB
and I2C, and the "ovcamchip" module for the image sensor. Make sure you are not
actually using any external "ovcamchip" module, given that the W996[87]CF
driver depends on the version of the module present in the official kernels.
The following options of the kernel configuration file must be enabled and
corresponding modules must be compiled:
# Multimedia devices
#
CONFIG_VIDEO_DEV=m
# I2C support
#
CONFIG_I2C=m
The I2C core module can be compiled statically in the kernel as well.
# OmniVision Camera Chip support
#
CONFIG_VIDEO_OVCAMCHIP=m
# USB support
#
CONFIG_USB=m
In addition, depending on the hardware being used, only one of the modules
below is necessary:
# USB Host Controller Drivers
#
CONFIG_USB_EHCI_HCD=m
CONFIG_USB_UHCI_HCD=m
CONFIG_USB_OHCI_HCD=m
And finally:
# USB Multimedia devices
#
CONFIG_USB_W9968CF=m
7. Module loading
=================
To use the driver, it is necessary to load the "w9968cf" module into memory
after every other module required.
Loading can be done this way, from root:
[root@localhost home]# modprobe usbcore
[root@localhost home]# modprobe i2c-core
[root@localhost home]# modprobe videodev
[root@localhost home]# modprobe w9968cf
At this point the pertinent devices should be recognized: "dmesg" can be used
to analyze kernel messages:
[user@localhost home]$ dmesg
There are a lot of parameters the module can use to change the default
settings for each device. To list every possible parameter with a brief
explanation about them and which syntax to use, it is recommended to run the
"modinfo" command:
[root@locahost home]# modinfo w9968cf
8. Module parameters
====================
Module parameters are listed below:
-------------------------------------------------------------------------------
Name: ovmod_load
Type: bool
Syntax: <0|1>
Description: Automatic 'ovcamchip' module loading: 0 disabled, 1 enabled.
If enabled, 'insmod' searches for the required 'ovcamchip'
module in the system, according to its configuration, and
loads that module automatically. This action is performed as
once soon as the 'w9968cf' module is loaded into memory.
Default: 1
Note: The kernel must be compiled with the CONFIG_KMOD option
enabled for the 'ovcamchip' module to be loaded and for
this parameter to be present.
-------------------------------------------------------------------------------
Name: simcams
Type: int
Syntax: <n>
Description: Number of cameras allowed to stream simultaneously.
n may vary from 0 to 32.
Default: 32
-------------------------------------------------------------------------------
Name: video_nr
Type: int array (min = 0, max = 32)
Syntax: <-1|n[,...]>
Description: Specify V4L minor mode number.
-1 = use next available
n = use minor number n
You can specify up to 32 cameras this way.
For example:
video_nr=-1,2,-1 would assign minor number 2 to the second
recognized camera and use auto for the first one and for every
other camera.
Default: -1
-------------------------------------------------------------------------------
Name: packet_size
Type: int array (min = 0, max = 32)
Syntax: <n[,...]>
Description: Specify the maximum data payload size in bytes for alternate
settings, for each device. n is scaled between 63 and 1023.
Default: 1023
-------------------------------------------------------------------------------
Name: max_buffers
Type: int array (min = 0, max = 32)
Syntax: <n[,...]>
Description: For advanced users.
Specify the maximum number of video frame buffers to allocate
for each device, from 2 to 32.
Default: 2
-------------------------------------------------------------------------------
Name: double_buffer
Type: bool array (min = 0, max = 32)
Syntax: <0|1[,...]>
Description: Hardware double buffering: 0 disabled, 1 enabled.
It should be enabled if you want smooth video output: if you
obtain out of sync. video, disable it, or try to
decrease the 'clockdiv' module parameter value.
Default: 1 for every device.
-------------------------------------------------------------------------------
Name: clamping
Type: bool array (min = 0, max = 32)
Syntax: <0|1[,...]>
Description: Video data clamping: 0 disabled, 1 enabled.
Default: 0 for every device.
-------------------------------------------------------------------------------
Name: filter_type
Type: int array (min = 0, max = 32)
Syntax: <0|1|2[,...]>
Description: Video filter type.
0 none, 1 (1-2-1) 3-tap filter, 2 (2-3-6-3-2) 5-tap filter.
The filter is used to reduce noise and aliasing artifacts
produced by the CCD or CMOS image sensor.
Default: 0 for every device.
-------------------------------------------------------------------------------
Name: largeview
Type: bool array (min = 0, max = 32)
Syntax: <0|1[,...]>
Description: Large view: 0 disabled, 1 enabled.
Default: 1 for every device.
-------------------------------------------------------------------------------
Name: upscaling
Type: bool array (min = 0, max = 32)
Syntax: <0|1[,...]>
Description: Software scaling (for non-compressed video only):
0 disabled, 1 enabled.
Disable it if you have a slow CPU or you don't have enough
memory.
Default: 0 for every device.
Note: If 'w9968cf-vpp' is not present, this parameter is set to 0.
-------------------------------------------------------------------------------
Name: decompression
Type: int array (min = 0, max = 32)
Syntax: <0|1|2[,...]>
Description: Software video decompression:
0 = disables decompression
(doesn't allow formats needing decompression).
1 = forces decompression
(allows formats needing decompression only).
2 = allows any permitted formats.
Formats supporting (de)compressed video are YUV422P and
YUV420P/YUV420 in any resolutions where width and height are
multiples of 16.
Default: 2 for every device.
Note: If 'w9968cf-vpp' is not present, forcing decompression is not
allowed; in this case this parameter is set to 2.
-------------------------------------------------------------------------------
Name: force_palette
Type: int array (min = 0, max = 32)
Syntax: <0|9|10|13|15|8|7|1|6|3|4|5[,...]>
Description: Force picture palette.
In order:
0 = Off - allows any of the following formats:
9 = UYVY 16 bpp - Original video, compression disabled
10 = YUV420 12 bpp - Original video, compression enabled
13 = YUV422P 16 bpp - Original video, compression enabled
15 = YUV420P 12 bpp - Original video, compression enabled
8 = YUVY 16 bpp - Software conversion from UYVY
7 = YUV422 16 bpp - Software conversion from UYVY
1 = GREY 8 bpp - Software conversion from UYVY
6 = RGB555 16 bpp - Software conversion from UYVY
3 = RGB565 16 bpp - Software conversion from UYVY
4 = RGB24 24 bpp - Software conversion from UYVY
5 = RGB32 32 bpp - Software conversion from UYVY
When not 0, this parameter will override 'decompression'.
Default: 0 for every device. Initial palette is 9 (UYVY).
Note: If 'w9968cf-vpp' is not present, this parameter is set to 9.
-------------------------------------------------------------------------------
Name: force_rgb
Type: bool array (min = 0, max = 32)
Syntax: <0|1[,...]>
Description: Read RGB video data instead of BGR:
1 = use RGB component ordering.
0 = use BGR component ordering.
This parameter has effect when using RGBX palettes only.
Default: 0 for every device.
-------------------------------------------------------------------------------
Name: autobright
Type: bool array (min = 0, max = 32)
Syntax: <0|1[,...]>
Description: Image sensor automatically changes brightness:
0 = no, 1 = yes
Default: 0 for every device.
-------------------------------------------------------------------------------
Name: autoexp
Type: bool array (min = 0, max = 32)
Syntax: <0|1[,...]>
Description: Image sensor automatically changes exposure:
0 = no, 1 = yes
Default: 1 for every device.
-------------------------------------------------------------------------------
Name: lightfreq
Type: int array (min = 0, max = 32)
Syntax: <50|60[,...]>
Description: Light frequency in Hz:
50 for European and Asian lighting, 60 for American lighting.
Default: 50 for every device.
-------------------------------------------------------------------------------
Name: bandingfilter
Type: bool array (min = 0, max = 32)
Syntax: <0|1[,...]>
Description: Banding filter to reduce effects of fluorescent
lighting:
0 disabled, 1 enabled.
This filter tries to reduce the pattern of horizontal
light/dark bands caused by some (usually fluorescent) lighting.
Default: 0 for every device.
-------------------------------------------------------------------------------
Name: clockdiv
Type: int array (min = 0, max = 32)
Syntax: <-1|n[,...]>
Description: Force pixel clock divisor to a specific value (for experts):
n may vary from 0 to 127.
-1 for automatic value.
See also the 'double_buffer' module parameter.
Default: -1 for every device.
-------------------------------------------------------------------------------
Name: backlight
Type: bool array (min = 0, max = 32)
Syntax: <0|1[,...]>
Description: Objects are lit from behind:
0 = no, 1 = yes
Default: 0 for every device.
-------------------------------------------------------------------------------
Name: mirror
Type: bool array (min = 0, max = 32)
Syntax: <0|1[,...]>
Description: Reverse image horizontally:
0 = no, 1 = yes
Default: 0 for every device.
-------------------------------------------------------------------------------
Name: monochrome
Type: bool array (min = 0, max = 32)
Syntax: <0|1[,...]>
Description: The image sensor is monochrome:
0 = no, 1 = yes
Default: 0 for every device.
-------------------------------------------------------------------------------
Name: brightness
Type: long array (min = 0, max = 32)
Syntax: <n[,...]>
Description: Set picture brightness (0-65535).
This parameter has no effect if 'autobright' is enabled.
Default: 31000 for every device.
-------------------------------------------------------------------------------
Name: hue
Type: long array (min = 0, max = 32)
Syntax: <n[,...]>
Description: Set picture hue (0-65535).
Default: 32768 for every device.
-------------------------------------------------------------------------------
Name: colour
Type: long array (min = 0, max = 32)
Syntax: <n[,...]>
Description: Set picture saturation (0-65535).
Default: 32768 for every device.
-------------------------------------------------------------------------------
Name: contrast
Type: long array (min = 0, max = 32)
Syntax: <n[,...]>
Description: Set picture contrast (0-65535).
Default: 50000 for every device.
-------------------------------------------------------------------------------
Name: whiteness
Type: long array (min = 0, max = 32)
Syntax: <n[,...]>
Description: Set picture whiteness (0-65535).
Default: 32768 for every device.
-------------------------------------------------------------------------------
Name: debug
Type: int
Syntax: <n>
Description: Debugging information level, from 0 to 6:
0 = none (use carefully)
1 = critical errors
2 = significant informations
3 = configuration or general messages
4 = warnings
5 = called functions
6 = function internals
Level 5 and 6 are useful for testing only, when only one
device is used.
Default: 2
-------------------------------------------------------------------------------
Name: specific_debug
Type: bool
Syntax: <0|1>
Description: Enable or disable specific debugging messages:
0 = print messages concerning every level <= 'debug' level.
1 = print messages concerning the level indicated by 'debug'.
Default: 0
-------------------------------------------------------------------------------
9. Contact information
======================
I may be contacted by e-mail at <luca.risolia@studio.unibo.it>.
I can accept GPG/PGP encrypted e-mail. My GPG key ID is 'FCE635A4'.
My public 1024-bit key should be available at your keyserver; the fingerprint
is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'.
10. Credits
==========
The development would not have proceed much further without having looked at
the source code of other drivers and without the help of several persons; in
particular:
- the I2C interface to kernel and high-level image sensor control routines have
been taken from the OV511 driver by Mark McClelland;
- memory management code has been copied from the bttv driver by Ralph Metzler,
Marcus Metzler and Gerd Knorr;
- the low-level I2C read function has been written by Frederic Jouault;
- the low-level I2C fast write function has been written by Piotr Czerczak.
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