mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-18 09:44:18 +08:00
2656312724
- Implement audio ioctl's and VIDIOC_ENUM_FRAMESIZES - Documentation updates - Generic improvements Signed-off-by: Luca Risolia <luca.risolia@studio.unibo.it> Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
316 lines
11 KiB
Plaintext
316 lines
11 KiB
Plaintext
|
|
ET61X[12]51 PC Camera Controllers
|
|
Driver for Linux
|
|
=================================
|
|
|
|
- Documentation -
|
|
|
|
|
|
Index
|
|
=====
|
|
1. Copyright
|
|
2. Disclaimer
|
|
3. License
|
|
4. Overview and features
|
|
5. Module dependencies
|
|
6. Module loading
|
|
7. Module parameters
|
|
8. Optional device control through "sysfs"
|
|
9. Supported devices
|
|
10. Notes for V4L2 application developers
|
|
11. Contact information
|
|
|
|
|
|
1. Copyright
|
|
============
|
|
Copyright (C) 2006-2007 by Luca Risolia <luca.risolia@studio.unibo.it>
|
|
|
|
|
|
2. Disclaimer
|
|
=============
|
|
Etoms is a trademark of Etoms Electronics Corp.
|
|
This software is not developed or sponsored by Etoms Electronics.
|
|
|
|
|
|
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 and features
|
|
========================
|
|
This driver supports the video interface of the devices mounting the ET61X151
|
|
or ET61X251 PC Camera Controllers.
|
|
|
|
It's worth to note that Etoms Electronics has never collaborated with the
|
|
author during the development of this project; despite several requests,
|
|
Etoms Electronics also refused to release enough detailed specifications of
|
|
the video compression engine.
|
|
|
|
The driver relies on the Video4Linux2 and USB core modules. It has been
|
|
designed to run properly on SMP systems as well.
|
|
|
|
The latest version of the ET61X[12]51 driver can be found at the following URL:
|
|
http://www.linux-projects.org/
|
|
|
|
Some of the features of the driver are:
|
|
|
|
- full compliance with the Video4Linux2 API (see also "Notes for V4L2
|
|
application developers" paragraph);
|
|
- available mmap or read/poll methods for video streaming through isochronous
|
|
data transfers;
|
|
- automatic detection of image sensor;
|
|
- support for any window resolutions and optional panning within the maximum
|
|
pixel area of image sensor;
|
|
- image downscaling with arbitrary scaling factors from 1 and 2 in both
|
|
directions (see "Notes for V4L2 application developers" paragraph);
|
|
- two different video formats for uncompressed or compressed data in low or
|
|
high compression quality (see also "Notes for V4L2 application developers"
|
|
paragraph);
|
|
- full support for the capabilities of every possible image sensors that can
|
|
be connected to the ET61X[12]51 bridges, including, for instance, red, green,
|
|
blue and global gain adjustments and exposure control (see "Supported
|
|
devices" paragraph for details);
|
|
- use of default color settings for sunlight conditions;
|
|
- dynamic I/O interface for both ET61X[12]51 and image sensor control (see
|
|
"Optional device control through 'sysfs'" paragraph);
|
|
- dynamic driver control thanks to various module parameters (see "Module
|
|
parameters" paragraph);
|
|
- up to 64 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
|
|
the system supports hotplugging;
|
|
- no known bugs.
|
|
|
|
|
|
5. Module dependencies
|
|
======================
|
|
For it to work properly, the driver needs kernel support for Video4Linux and
|
|
USB.
|
|
|
|
The following options of the kernel configuration file must be enabled and
|
|
corresponding modules must be compiled:
|
|
|
|
# Multimedia devices
|
|
#
|
|
CONFIG_VIDEO_DEV=m
|
|
|
|
To enable advanced debugging functionality on the device through /sysfs:
|
|
|
|
# Multimedia devices
|
|
#
|
|
CONFIG_VIDEO_ADV_DEBUG=y
|
|
|
|
# USB support
|
|
#
|
|
CONFIG_USB=m
|
|
|
|
In addition, depending on the hardware being used, the modules below are
|
|
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_ET61X251=m
|
|
|
|
|
|
6. Module loading
|
|
=================
|
|
To use the driver, it is necessary to load the "et61x251" module into memory
|
|
after every other module required: "videodev", "v4l2_common", "compat_ioctl32",
|
|
"usbcore" and, depending on the USB host controller you have, "ehci-hcd",
|
|
"uhci-hcd" or "ohci-hcd".
|
|
|
|
Loading can be done as shown below:
|
|
|
|
[root@localhost home]# modprobe et61x251
|
|
|
|
At this point the devices should be recognized. You can invoke "dmesg" to
|
|
analyze kernel messages and verify that the loading process has gone well:
|
|
|
|
[user@localhost home]$ dmesg
|
|
|
|
|
|
7. Module parameters
|
|
====================
|
|
Module parameters are listed below:
|
|
-------------------------------------------------------------------------------
|
|
Name: video_nr
|
|
Type: short array (min = 0, max = 64)
|
|
Syntax: <-1|n[,...]>
|
|
Description: Specify V4L2 minor mode number:
|
|
-1 = use next available
|
|
n = use minor number n
|
|
You can specify up to 64 cameras this way.
|
|
For example:
|
|
video_nr=-1,2,-1 would assign minor number 2 to the second
|
|
registered camera and use auto for the first one and for every
|
|
other camera.
|
|
Default: -1
|
|
-------------------------------------------------------------------------------
|
|
Name: force_munmap
|
|
Type: bool array (min = 0, max = 64)
|
|
Syntax: <0|1[,...]>
|
|
Description: Force the application to unmap previously mapped buffer memory
|
|
before calling any VIDIOC_S_CROP or VIDIOC_S_FMT ioctl's. Not
|
|
all the applications support this feature. This parameter is
|
|
specific for each detected camera.
|
|
0 = do not force memory unmapping
|
|
1 = force memory unmapping (save memory)
|
|
Default: 0
|
|
-------------------------------------------------------------------------------
|
|
Name: frame_timeout
|
|
Type: uint array (min = 0, max = 64)
|
|
Syntax: <n[,...]>
|
|
Description: Timeout for a video frame in seconds. This parameter is
|
|
specific for each detected camera. This parameter can be
|
|
changed at runtime thanks to the /sys filesystem interface.
|
|
Default: 2
|
|
-------------------------------------------------------------------------------
|
|
Name: debug
|
|
Type: ushort
|
|
Syntax: <n>
|
|
Description: Debugging information level, from 0 to 3:
|
|
0 = none (use carefully)
|
|
1 = critical errors
|
|
2 = significant informations
|
|
3 = more verbose messages
|
|
Level 3 is useful for testing only, when only one device
|
|
is used at the same time. It also shows some more informations
|
|
about the hardware being detected. This module parameter can be
|
|
changed at runtime thanks to the /sys filesystem interface.
|
|
Default: 2
|
|
-------------------------------------------------------------------------------
|
|
|
|
|
|
8. Optional device control through "sysfs"
|
|
==========================================
|
|
If the kernel has been compiled with the CONFIG_VIDEO_ADV_DEBUG option enabled,
|
|
it is possible to read and write both the ET61X[12]51 and the image sensor
|
|
registers by using the "sysfs" filesystem interface.
|
|
|
|
There are four files in the /sys/class/video4linux/videoX directory for each
|
|
registered camera: "reg", "val", "i2c_reg" and "i2c_val". The first two files
|
|
control the ET61X[12]51 bridge, while the other two control the sensor chip.
|
|
"reg" and "i2c_reg" hold the values of the current register index where the
|
|
following reading/writing operations are addressed at through "val" and
|
|
"i2c_val". Their use is not intended for end-users, unless you know what you
|
|
are doing. Remember that you must be logged in as root before writing to them.
|
|
|
|
As an example, suppose we were to want to read the value contained in the
|
|
register number 1 of the sensor register table - which is usually the product
|
|
identifier - of the camera registered as "/dev/video0":
|
|
|
|
[root@localhost #] cd /sys/class/video4linux/video0
|
|
[root@localhost #] echo 1 > i2c_reg
|
|
[root@localhost #] cat i2c_val
|
|
|
|
Note that if the sensor registers cannot be read, "cat" will fail.
|
|
To avoid race conditions, all the I/O accesses to the files are serialized.
|
|
|
|
|
|
9. Supported devices
|
|
====================
|
|
None of the names of the companies as well as their products will be mentioned
|
|
here. They have never collaborated with the author, so no advertising.
|
|
|
|
From the point of view of a driver, what unambiguously identify a device are
|
|
its vendor and product USB identifiers. Below is a list of known identifiers of
|
|
devices mounting the ET61X[12]51 PC camera controllers:
|
|
|
|
Vendor ID Product ID
|
|
--------- ----------
|
|
0x102c 0x6151
|
|
0x102c 0x6251
|
|
0x102c 0x6253
|
|
0x102c 0x6254
|
|
0x102c 0x6255
|
|
0x102c 0x6256
|
|
0x102c 0x6257
|
|
0x102c 0x6258
|
|
0x102c 0x6259
|
|
0x102c 0x625a
|
|
0x102c 0x625b
|
|
0x102c 0x625c
|
|
0x102c 0x625d
|
|
0x102c 0x625e
|
|
0x102c 0x625f
|
|
0x102c 0x6260
|
|
0x102c 0x6261
|
|
0x102c 0x6262
|
|
0x102c 0x6263
|
|
0x102c 0x6264
|
|
0x102c 0x6265
|
|
0x102c 0x6266
|
|
0x102c 0x6267
|
|
0x102c 0x6268
|
|
0x102c 0x6269
|
|
|
|
The following image sensors are supported:
|
|
|
|
Model Manufacturer
|
|
----- ------------
|
|
TAS5130D1B Taiwan Advanced Sensor Corporation
|
|
|
|
All the available control settings of each image sensor are supported through
|
|
the V4L2 interface.
|
|
|
|
|
|
10. Notes for V4L2 application developers
|
|
=========================================
|
|
This driver follows the V4L2 API specifications. In particular, it enforces two
|
|
rules:
|
|
|
|
- exactly one I/O method, either "mmap" or "read", is associated with each
|
|
file descriptor. Once it is selected, the application must close and reopen the
|
|
device to switch to the other I/O method;
|
|
|
|
- although it is not mandatory, previously mapped buffer memory should always
|
|
be unmapped before calling any "VIDIOC_S_CROP" or "VIDIOC_S_FMT" ioctl's.
|
|
The same number of buffers as before will be allocated again to match the size
|
|
of the new video frames, so you have to map the buffers again before any I/O
|
|
attempts on them.
|
|
|
|
Consistently with the hardware limits, this driver also supports image
|
|
downscaling with arbitrary scaling factors from 1 and 2 in both directions.
|
|
However, the V4L2 API specifications don't correctly define how the scaling
|
|
factor can be chosen arbitrarily by the "negotiation" of the "source" and
|
|
"target" rectangles. To work around this flaw, we have added the convention
|
|
that, during the negotiation, whenever the "VIDIOC_S_CROP" ioctl is issued, the
|
|
scaling factor is restored to 1.
|
|
|
|
This driver supports two different video formats: the first one is the "8-bit
|
|
Sequential Bayer" format and can be used to obtain uncompressed video data
|
|
from the device through the current I/O method, while the second one provides
|
|
"raw" compressed video data (without frame headers not related to the
|
|
compressed data). The current compression quality may vary from 0 to 1 and can
|
|
be selected or queried thanks to the VIDIOC_S_JPEGCOMP and VIDIOC_G_JPEGCOMP
|
|
V4L2 ioctl's.
|
|
|
|
|
|
11. Contact information
|
|
=======================
|
|
The author may be contacted by e-mail at <luca.risolia@studio.unibo.it>.
|
|
|
|
GPG/PGP encrypted e-mail's are accepted. The GPG key ID of the author is
|
|
'FCE635A4'; the public 1024-bit key should be available at any keyserver;
|
|
the fingerprint is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'.
|