vserver 1.9.3

[linux-2.6.git] / Documentation / usb / sn9c102.txt

diff --git a/Documentation/usb/sn9c102.txt b/Documentation/usb/sn9c102.txt
index 65018c8..3999069 100644 (file)
--- a/Documentation/usb/sn9c102.txt
+++ b/Documentation/usb/sn9c102.txt
@@ -14,10 +14,10 @@ Index
 4.  Module dependencies
 5.  Module loading
 6.  Module parameters
 4.  Module dependencies
 5.  Module loading
 6.  Module parameters

-7.  Device control through "sysfs"
+7.  Optional device control through "sysfs"

 8.  Supported devices
 9.  How to add support for new image sensors
 8.  Supported devices
 9.  How to add support for new image sensors

-10. Note for V4L2 developers
+10. Notes for V4L2 application developers

 11. Contact information
 12. Credits
 
 11. Contact information
 12. Credits
 


@@ -142,23 +142,21 @@ Description:    Debugging information level, from 0 to 3:
                 1 = critical errors
                 2 = significant informations
                 3 = more verbose messages
                 1 = critical errors
                 2 = significant informations
                 3 = more verbose messages

-                Level 3 is useful for testing only, when just one device
+                Level 3 is useful for testing only, when only one device

                 is used.
 Default:        2
 -------------------------------------------------------------------------------
 
 
                 is used.
 Default:        2
 -------------------------------------------------------------------------------
 
 

-7. Device control through "sysfs"
-=================================
+7. Optional device control through "sysfs"
+==========================================

 It is possible to read and write both the SN9C10[12] and the image sensor
 registers by using the "sysfs" filesystem interface.
 
 It is possible to read and write both the SN9C10[12] and the image sensor
 registers by using the "sysfs" filesystem interface.
 

-Every time a supported device is recognized, read-only files named "redblue"
-and "green" are created in the /sys/class/video4linux/videoX directory. You can
-set the red, blue and green channel's gain by writing the desired value to
-them. The value may range from 0 to 15 for each channel; this means that
-"redblue" accepts 8-bit values, where the low 4 bits are reserved for red and
-the others for blue.
+Every time a supported device is recognized, a read-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.

 
 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
 
 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


@@ -208,7 +206,7 @@ Vendor ID  Product ID
 0xc45      0x6029
 0xc45      0x602a
 0xc45      0x602c
 0xc45      0x6029
 0xc45      0x602a
 0xc45      0x602c

-0xc45      0x8001
+0xc45      0x6030

 
 The list above does NOT imply that all those devices work with this driver: up
 until now only the ones that mount the following image sensors are supported.
 
 The list above does NOT imply that all those devices work with this driver: up
 until now only the ones that mount the following image sensors are supported.


@@ -217,6 +215,7 @@ Kernel messages will always tell you whether this is the case:
 Model       Manufacturer
 -----       ------------
 PAS106B     PixArt Imaging Inc.
 Model       Manufacturer
 -----       ------------
 PAS106B     PixArt Imaging Inc.

+PAS202BCB   PixArt Imaging Inc.

 TAS5110C1B  Taiwan Advanced Sensor Corporation
 TAS5130D1B  Taiwan Advanced Sensor Corporation
 
 TAS5110C1B  Taiwan Advanced Sensor Corporation
 TAS5130D1B  Taiwan Advanced Sensor Corporation
 


@@ -239,23 +238,31 @@ have created for this purpose, which is present in "sn9c102_sensor.h"
 (documentation is included there). As an example, have a look at the code in
 "sn9c102_pas106b.c", which uses the mentioned interface.
 
 (documentation is included there). As an example, have a look at the code in
 "sn9c102_pas106b.c", which uses the mentioned interface.
 

-At the moment, not yet supported image sensors are: PAS202B (VGA),
-HV7131[D|E1] (VGA), MI03 (VGA), OV7620 (VGA).
+At the moment, not yet supported image sensors are: HV7131[D|E1] (VGA),
+MI03 (VGA), OV7620 (VGA).

 
 
 
 

-10. Note for V4L2 developers
-============================
+10. Notes for V4L2 application developers
+=========================================

 This driver follows the V4L2 API specifications. In particular, it enforces two
 rules:
 
 This driver follows the V4L2 API specifications. In particular, it enforces two
 rules:
 

-1) Exactly one I/O method, either "mmap" or "read", is associated with each
+- 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
 file descriptor. Once it is selected, the application must close and reopen the

-device to switch to the other I/O method.
+device to switch to the other I/O method;

 
 

-2) Previously mapped buffer memory must always be unmapped before calling any
-of the "VIDIOC_S_CROP", "VIDIOC_TRY_FMT" and "VIDIOC_S_FMT" ioctl's. In case,
-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 them again before any I/O attempts.
+- previously mapped buffer memory must always be unmapped before calling any
+of the "VIDIOC_S_CROP", "VIDIOC_TRY_FMT" and "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 them again before any I/O attempts.
+
+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 choosen 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.

 
 
 11. Contact information
 
 
 11. Contact information


@@ -273,4 +280,6 @@ I would thank the following persons:
 
 - Stefano Mozzi, who donated 45 EU;
 - Luca Capello for the donation of a webcam;
 
 - Stefano Mozzi, who donated 45 EU;
 - Luca Capello for the donation of a webcam;

-- Mizuno Takafumi for the donation of a webcam.
+- Mizuno Takafumi for the donation of a webcam;
+- Carlos Eduardo Medaglia Dyonisio, who added the support for the PAS202BCB
+  image sensor.