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diff --git a/Documentation/video4linux/sn9c102.txt b/Documentation/video4linux/sn9c102.txt new file mode 100644 index 0000000..73de405 --- /dev/null +++ b/Documentation/video4linux/sn9c102.txt @@ -0,0 +1,592 @@ + + SN9C1xx 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. Video frame formats +12. Contact information +13. Credits + + +1. Copyright +============ +Copyright (C) 2004-2007 by Luca Risolia <luca.risolia@studio.unibo.it> + + +2. Disclaimer +============= +SONiX is a trademark of SONiX Technology Company Limited, inc. +This software is not sponsored or developed by SONiX. + + +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 attempts to support the video interface of the devices assembling +the SONiX SN9C101, SN9C102, SN9C103, SN9C105 and SN9C120 PC Camera Controllers +("SN9C1xx" from now on). + +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 SN9C1xx 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 built-in microphone interface; +- support for any window resolutions and optional panning within the maximum + pixel area of image sensor; +- image downscaling with arbitrary scaling factors from 1, 2 and 4 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" + and "Video frame formats" paragraphs); +- full support for the capabilities of many of the possible image sensors that + can be connected to the SN9C1xx bridges, including, for instance, red, green, + blue and global gain adjustments and exposure (see "Supported devices" + paragraph for details); +- use of default color settings for sunlight conditions; +- dynamic I/O interface for both SN9C1xx and image sensor control and + monitoring (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 + +The SN9C103, SN9c105 and SN9C120 controllers also provide a built-in microphone +interface. It is supported by the USB Audio driver thanks to the ALSA API: + + # Sound + # + CONFIG_SOUND=y + + # Advanced Linux Sound Architecture + # + CONFIG_SND=m + + # USB devices + # + CONFIG_SND_USB_AUDIO=m + +And finally: + + # USB Multimedia devices + # + CONFIG_USB_SN9C102=m + + +6. Module loading +================= +To use the driver, it is necessary to load the "sn9c102" 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 sn9c102 + +Note that the module is called "sn9c102" for historic reasons, although it +does not just support the SN9C102. + +At this point all the devices supported by the driver and connected to the USB +ports should be recognized. You can invoke "dmesg" to analyze kernel messages +and verify that the loading process has gone well: + + [user@localhost home]$ dmesg + +or, to isolate all the kernel messages generated by the driver: + + [user@localhost home]$ dmesg | grep sn9c102 + + +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 + recognized 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: <0|n[,...]> +Description: Timeout for a video frame in seconds before returning an I/O + error; 0 for infinity. This parameter is specific for each + detected camera and 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. It also shows some more + informations about the hardware being detected. + This parameter can be changed at runtime thanks to the /sys + filesystem interface. +Default: 2 +------------------------------------------------------------------------------- + + +8. Optional device control through "sysfs" [1] +========================================== +If the kernel has been compiled with the CONFIG_VIDEO_ADV_DEBUG option enabled, +it is possible to read and write both the SN9C1xx and the image sensor +registers by using the "sysfs" filesystem interface. + +Every time a supported device is recognized, a write-only file named "green" is +created in the /sys/class/video4linux/videoX directory. You can set the green +channel's gain by writing the desired value to it. The value may range from 0 +to 15 for the SN9C101 or SN9C102 bridges, from 0 to 127 for the SN9C103, +SN9C105 and SN9C120 bridges. +Similarly, only for the SN9C103, SN9C105 and SN9C120 controllers, blue and red +gain control files are available in the same directory, for which accepted +values may range from 0 to 127. + +There are other four entries in the directory above for each registered camera: +"reg", "val", "i2c_reg" and "i2c_val". The first two files control the +SN9C1xx 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. Note that "i2c_reg" and "i2c_val" will not +be created if the sensor does not actually support the standard I2C protocol or +its registers are not 8-bit long. Also, 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 "cat" will fail if sensor registers cannot be read. + +Now let's set the green gain's register of the SN9C101 or SN9C102 chips to 2: + + [root@localhost #] echo 0x11 > reg + [root@localhost #] echo 2 > val + +Note that the SN9C1xx always returns 0 when some of its registers are read. +To avoid race conditions, all the I/O accesses to the above files are +serialized. +The sysfs interface also provides the "frame_header" entry, which exports the +frame header of the most recent requested and captured video frame. The header +is always 18-bytes long and is appended to every video frame by the SN9C1xx +controllers. As an example, this additional information can be used by the user +application for implementing auto-exposure features via software. + +The following table describes the frame header exported by the SN9C101 and +SN9C102: + +Byte # Value or bits Description +------ ------------- ----------- +0x00 0xFF Frame synchronisation pattern +0x01 0xFF Frame synchronisation pattern +0x02 0x00 Frame synchronisation pattern +0x03 0xC4 Frame synchronisation pattern +0x04 0xC4 Frame synchronisation pattern +0x05 0x96 Frame synchronisation pattern +0x06 [3:0] Read channel gain control = (1+R_GAIN/8) + [7:4] Blue channel gain control = (1+B_GAIN/8) +0x07 [ 0 ] Compression mode. 0=No compression, 1=Compression enabled + [2:1] Maximum scale factor for compression + [ 3 ] 1 = USB fifo(2K bytes) is full + [ 4 ] 1 = Digital gain is finish + [ 5 ] 1 = Exposure is finish + [7:6] Frame index +0x08 [7:0] Y sum inside Auto-Exposure area (low-byte) +0x09 [7:0] Y sum inside Auto-Exposure area (high-byte) + where Y sum = (R/4 + 5G/16 + B/8) / 32 +0x0A [7:0] Y sum outside Auto-Exposure area (low-byte) +0x0B [7:0] Y sum outside Auto-Exposure area (high-byte) + where Y sum = (R/4 + 5G/16 + B/8) / 128 +0x0C 0xXX Not used +0x0D 0xXX Not used +0x0E 0xXX Not used +0x0F 0xXX Not used +0x10 0xXX Not used +0x11 0xXX Not used + +The following table describes the frame header exported by the SN9C103: + +Byte # Value or bits Description +------ ------------- ----------- +0x00 0xFF Frame synchronisation pattern +0x01 0xFF Frame synchronisation pattern +0x02 0x00 Frame synchronisation pattern +0x03 0xC4 Frame synchronisation pattern +0x04 0xC4 Frame synchronisation pattern +0x05 0x96 Frame synchronisation pattern +0x06 [6:0] Read channel gain control = (1/2+R_GAIN/64) +0x07 [6:0] Blue channel gain control = (1/2+B_GAIN/64) + [7:4] +0x08 [ 0 ] Compression mode. 0=No compression, 1=Compression enabled + [2:1] Maximum scale factor for compression + [ 3 ] 1 = USB fifo(2K bytes) is full + [ 4 ] 1 = Digital gain is finish + [ 5 ] 1 = Exposure is finish + [7:6] Frame index +0x09 [7:0] Y sum inside Auto-Exposure area (low-byte) +0x0A [7:0] Y sum inside Auto-Exposure area (high-byte) + where Y sum = (R/4 + 5G/16 + B/8) / 32 +0x0B [7:0] Y sum outside Auto-Exposure area (low-byte) +0x0C [7:0] Y sum outside Auto-Exposure area (high-byte) + where Y sum = (R/4 + 5G/16 + B/8) / 128 +0x0D [1:0] Audio frame number + [ 2 ] 1 = Audio is recording +0x0E [7:0] Audio summation (low-byte) +0x0F [7:0] Audio summation (high-byte) +0x10 [7:0] Audio sample count +0x11 [7:0] Audio peak data in audio frame + +The AE area (sx, sy, ex, ey) in the active window can be set by programming the +registers 0x1c, 0x1d, 0x1e and 0x1f of the SN9C1xx controllers, where one unit +corresponds to 32 pixels. + +[1] The frame headers exported by the SN9C105 and SN9C120 are not described. + + +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 assembling the SN9C1xx PC camera controllers: + +Vendor ID Product ID +--------- ---------- +0x0458 0x7025 +0x045e 0x00f5 +0x045e 0x00f7 +0x0471 0x0327 +0x0471 0x0328 +0x0c45 0x6001 +0x0c45 0x6005 +0x0c45 0x6007 +0x0c45 0x6009 +0x0c45 0x600d +0x0c45 0x6011 +0x0c45 0x6019 +0x0c45 0x6024 +0x0c45 0x6025 +0x0c45 0x6028 +0x0c45 0x6029 +0x0c45 0x602a +0x0c45 0x602b +0x0c45 0x602c +0x0c45 0x602d +0x0c45 0x602e +0x0c45 0x6030 +0x0c45 0x603f +0x0c45 0x6080 +0x0c45 0x6082 +0x0c45 0x6083 +0x0c45 0x6088 +0x0c45 0x608a +0x0c45 0x608b +0x0c45 0x608c +0x0c45 0x608e +0x0c45 0x608f +0x0c45 0x60a0 +0x0c45 0x60a2 +0x0c45 0x60a3 +0x0c45 0x60a8 +0x0c45 0x60aa +0x0c45 0x60ab +0x0c45 0x60ac +0x0c45 0x60ae +0x0c45 0x60af +0x0c45 0x60b0 +0x0c45 0x60b2 +0x0c45 0x60b3 +0x0c45 0x60b8 +0x0c45 0x60ba +0x0c45 0x60bb +0x0c45 0x60bc +0x0c45 0x60be +0x0c45 0x60c0 +0x0c45 0x60c2 +0x0c45 0x60c8 +0x0c45 0x60cc +0x0c45 0x60ea +0x0c45 0x60ec +0x0c45 0x60ef +0x0c45 0x60fa +0x0c45 0x60fb +0x0c45 0x60fc +0x0c45 0x60fe +0x0c45 0x6102 +0x0c45 0x6108 +0x0c45 0x610f +0x0c45 0x6130 +0x0c45 0x6138 +0x0c45 0x613a +0x0c45 0x613b +0x0c45 0x613c +0x0c45 0x613e + +The list above does not imply that all those devices work with this driver: up +until now only the ones that assemble the following pairs of SN9C1xx bridges +and image sensors are supported; kernel messages will always tell you whether +this is the case (see "Module loading" paragraph): + +Image sensor / SN9C1xx bridge | SN9C10[12] SN9C103 SN9C105 SN9C120 +------------------------------------------------------------------------------- +HV7131D Hynix Semiconductor | Yes No No No +HV7131R Hynix Semiconductor | No Yes Yes Yes +MI-0343 Micron Technology | Yes No No No +MI-0360 Micron Technology | No Yes Yes Yes +OV7630 OmniVision Technologies | Yes Yes Yes Yes +OV7660 OmniVision Technologies | No No Yes Yes +PAS106B PixArt Imaging | Yes No No No +PAS202B PixArt Imaging | Yes Yes No No +TAS5110C1B Taiwan Advanced Sensor | Yes No No No +TAS5110D Taiwan Advanced Sensor | Yes No No No +TAS5130D1B Taiwan Advanced Sensor | Yes No No No + +"Yes" means that the pair is supported by the driver, while "No" means that the +pair does not exist or is not supported by the driver. + +Only some of the available control settings of each image sensor are supported +through the V4L2 interface. + +Donations of new models for further testing and support would be much +appreciated. Non-available hardware will not be supported by the author of this +driver. + + +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, 2 and 4 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 +either "raw" compressed video data (without frame headers not related to the +compressed data) or standard JPEG (with frame headers). The 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. For maximum flexibility, +both the default active video format and the default compression quality +depend on how the image sensor being used is initialized. + + +11. Video frame formats [1] +======================= +The SN9C1xx PC Camera Controllers can send images in two possible video +formats over the USB: either native "Sequential RGB Bayer" or compressed. +The compression is used to achieve high frame rates. With regard to the +SN9C101, SN9C102 and SN9C103, the compression is based on the Huffman encoding +algorithm described below, while with regard to the SN9C105 and SN9C120 the +compression is based on the JPEG standard. +The current video format may be selected or queried from the user application +by calling the VIDIOC_S_FMT or VIDIOC_G_FMT ioctl's, as described in the V4L2 +API specifications. + +The name "Sequential Bayer" indicates the organization of the red, green and +blue pixels in one video frame. Each pixel is associated with a 8-bit long +value and is disposed in memory according to the pattern shown below: + +B[0] G[1] B[2] G[3] ... B[m-2] G[m-1] +G[m] R[m+1] G[m+2] R[m+2] ... G[2m-2] R[2m-1] +... +... B[(n-1)(m-2)] G[(n-1)(m-1)] +... G[n(m-2)] R[n(m-1)] + +The above matrix also represents the sequential or progressive read-out mode of +the (n, m) Bayer color filter array used in many CCD or CMOS image sensors. + +The Huffman compressed video frame consists of a bitstream that encodes for +every R, G, or B pixel the difference between the value of the pixel itself and +some reference pixel value. Pixels are organised in the Bayer pattern and the +Bayer sub-pixels are tracked individually and alternatingly. For example, in +the first line values for the B and G1 pixels are alternatingly encoded, while +in the second line values for the G2 and R pixels are alternatingly encoded. + +The pixel reference value is calculated as follows: +- the 4 top left pixels are encoded in raw uncompressed 8-bit format; +- the value in the top two rows is the value of the pixel left of the current + pixel; +- the value in the left column is the value of the pixel above the current + pixel; +- for all other pixels, the reference value is the average of the value of the + pixel on the left and the value of the pixel above the current pixel; +- there is one code in the bitstream that specifies the value of a pixel + directly (in 4-bit resolution); +- pixel values need to be clamped inside the range [0..255] for proper + decoding. + +The algorithm purely describes the conversion from compressed Bayer code used +in the SN9C101, SN9C102 and SN9C103 chips to uncompressed Bayer. Additional +steps are required to convert this to a color image (i.e. a color interpolation +algorithm). + +The following Huffman codes have been found: +0: +0 (relative to reference pixel value) +100: +4 +101: -4? +1110xxxx: set absolute value to xxxx.0000 +1101: +11 +1111: -11 +11001: +20 +110000: -20 +110001: ??? - these codes are apparently not used + +[1] The Huffman compression algorithm has been reverse-engineered and + documented by Bertrik Sikken. + + +12. 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'. + + +13. Credits +=========== +Many thanks to following persons for their contribute (listed in alphabetical +order): + +- David Anderson for the donation of a webcam; +- Luca Capello for the donation of a webcam; +- Philippe Coval for having helped testing the PAS202BCA image sensor; +- Joao Rodrigo Fuzaro, Joao Limirio, Claudio Filho and Caio Begotti for the + donation of a webcam; +- Dennis Heitmann for the donation of a webcam; +- Jon Hollstrom for the donation of a webcam; +- Nick McGill for the donation of a webcam; +- Carlos Eduardo Medaglia Dyonisio, who added the support for the PAS202BCB + image sensor; +- Stefano Mozzi, who donated 45 EU; +- Andrew Pearce for the donation of a webcam; +- John Pullan for the donation of a webcam; +- Bertrik Sikken, who reverse-engineered and documented the Huffman compression + algorithm used in the SN9C101, SN9C102 and SN9C103 controllers and + implemented the first decoder; +- Ronny Standke for the donation of a webcam; +- Mizuno Takafumi for the donation of a webcam; +- an "anonymous" donator (who didn't want his name to be revealed) for the + donation of a webcam. +- an anonymous donator for the donation of four webcams and two boards with ten + image sensors. |
