aboutsummaryrefslogtreecommitdiff
path: root/xorg-server/hw/xfree86/ddc/DDC.HOWTO
diff options
context:
space:
mode:
Diffstat (limited to 'xorg-server/hw/xfree86/ddc/DDC.HOWTO')
-rw-r--r--xorg-server/hw/xfree86/ddc/DDC.HOWTO194
1 files changed, 97 insertions, 97 deletions
diff --git a/xorg-server/hw/xfree86/ddc/DDC.HOWTO b/xorg-server/hw/xfree86/ddc/DDC.HOWTO
index 54fbe73ad..1d06ca124 100644
--- a/xorg-server/hw/xfree86/ddc/DDC.HOWTO
+++ b/xorg-server/hw/xfree86/ddc/DDC.HOWTO
@@ -1,97 +1,97 @@
- DDC.HOWTO
-
- This file describes how to add DDC support to a chipset driver.
-
-1) DDC INITIALIZATION
-
- When implementing DDC in the driver one has the choice between
- DDC1 and DDC2.
- DDC1 data is continuously transmitted by a DDC1 capable display
- device. The data is send serially over a data line; the Vsync
- signal serves as clock. Only one EDID 1.x data block can be
- transmitted using DDC1. Since transmission of an EDID1 block
- using a regular Vsync frequency would take up several seconds
- the driver can increase the Vsync frequency to up to 25 kHz as
- soon as it detects DDC1 activity on the data line.
- DDC2 data is transmitted using the I2C protocol. This requires
- an additional clock line. DDC2 is capable of transmitting EDID1
- and EDID2 block as well as a VDIF block on display devices that
- support these.
- Display devices switch into the DDC2 mode as soon as they detect
- activity on the DDC clock line. Once the are in DDC2 mode they
- stop transmitting DDC1 signals until the next power cycle.
-
- Some graphics chipset configurations which are not capable of
- DDC2 might still be able to read DDC1 data. Where available
- DDC2 it is preferable.
-
- All relevant prototypes and defines are in xf86DDC.h.
- DDC2 additionally requires I2C support. The I2C prototypes
- are in xf86i2c.h.
-
- DDC1 Support:
-
- The driver has to provide a read function which waits for the
- end of the next Vsync signal and reads in and returns the status
- of the DDC line:
-
- unsigned int XXX_ddc1Read(ScrnInfoPtr pScrn)
-
- Additionally a function is required to increase the Vsync
- frequency to max. 25 kHz.
-
- void XXX_ddc1SetSpeed(ScrnInfoPtr pScrn, xf86ddcSpeed speed)
-
- If the speed argument is DDC_FAST the function should increase
- the Vsync frequency on DDC_SLOW it should restore the original
- value. For convenience a generic ddc1SetSpeed() function is provided
- in the vga module for VGA-like chipsets.
-
- void vgaHWddc1SetSpeed(ScrnInfoPtr pScrn, sf86ddcSpeed speed).
-
- To read out the DDC1 data the driver should call
-
- xf86MonPtr xf86DoEDID_DDC1(int scrnIndex,
- void (*DDC1SetSpeed)(ScrnInfoPtr, xf86ddcSpeed),
- unsigned int (*DDC1Read)(ScrnInfoPtr))
-
- in PreInit(). DDC1SetSpeed is a pointer to the SetSpeed()
- function, DDC1Read has to point to the DDC1 read function.
- The function will return a pointer to the xf86Monitor structure
- which contains all information retrieved by DDC.
- NULL will be returned on failure.
-
- DDC2 Support
-
- To read out DDC2 information I2C has to be initialized first.
- (See documentation for the i2c module).
- The function
-
- xf86MonPtr xf86DoEDID_DDC2(int scrnIndex, I2CBusPtr pBus)
-
- is provided to read out and process DDC2 data. A pointer
- to the I2CBusRec of the appropriate I2C Bus has to be passed
- as the second argument.
- The function will return a pointer to the xf86Monitor structure
- which contains all information retrieved by DDC.
- NULL will be returned on failure.
-
- Printing monitor parameters
-
- To print out the information contained in the xf86Monitor
- structure the function
-
- xf86MonPtr xf86PrintEDID(xf86MonPtr monitor)
-
- is provided.
-
- Further processing of the xf86Monitor structure is not yet
- implemented. However, it is planned to use the information
- about video modes, gamma values etc.
- Therefore it is strongly recommended to read out DDC data
- before any video mode processing is done.
-
-
-
-
-$XFree86: xc/programs/Xserver/hw/xfree86/ddc/DDC.HOWTO,v 1.2 1998/12/06 13:30:39 dawes Exp $
+ DDC.HOWTO
+
+ This file describes how to add DDC support to a chipset driver.
+
+1) DDC INITIALIZATION
+
+ When implementing DDC in the driver one has the choice between
+ DDC1 and DDC2.
+ DDC1 data is continuously transmitted by a DDC1 capable display
+ device. The data is send serially over a data line; the Vsync
+ signal serves as clock. Only one EDID 1.x data block can be
+ transmitted using DDC1. Since transmission of an EDID1 block
+ using a regular Vsync frequency would take up several seconds
+ the driver can increase the Vsync frequency to up to 25 kHz as
+ soon as it detects DDC1 activity on the data line.
+ DDC2 data is transmitted using the I2C protocol. This requires
+ an additional clock line. DDC2 is capable of transmitting EDID1
+ and EDID2 block as well as a VDIF block on display devices that
+ support these.
+ Display devices switch into the DDC2 mode as soon as they detect
+ activity on the DDC clock line. Once the are in DDC2 mode they
+ stop transmitting DDC1 signals until the next power cycle.
+
+ Some graphics chipset configurations which are not capable of
+ DDC2 might still be able to read DDC1 data. Where available
+ DDC2 it is preferable.
+
+ All relevant prototypes and defines are in xf86DDC.h.
+ DDC2 additionally requires I2C support. The I2C prototypes
+ are in xf86i2c.h.
+
+ DDC1 Support:
+
+ The driver has to provide a read function which waits for the
+ end of the next Vsync signal and reads in and returns the status
+ of the DDC line:
+
+ unsigned int XXX_ddc1Read(ScrnInfoPtr pScrn)
+
+ Additionally a function is required to increase the Vsync
+ frequency to max. 25 kHz.
+
+ void XXX_ddc1SetSpeed(ScrnInfoPtr pScrn, xf86ddcSpeed speed)
+
+ If the speed argument is DDC_FAST the function should increase
+ the Vsync frequency on DDC_SLOW it should restore the original
+ value. For convenience a generic ddc1SetSpeed() function is provided
+ in the vga module for VGA-like chipsets.
+
+ void vgaHWddc1SetSpeed(ScrnInfoPtr pScrn, sf86ddcSpeed speed).
+
+ To read out the DDC1 data the driver should call
+
+ xf86MonPtr xf86DoEDID_DDC1(int scrnIndex,
+ void (*DDC1SetSpeed)(ScrnInfoPtr, xf86ddcSpeed),
+ unsigned int (*DDC1Read)(ScrnInfoPtr))
+
+ in PreInit(). DDC1SetSpeed is a pointer to the SetSpeed()
+ function, DDC1Read has to point to the DDC1 read function.
+ The function will return a pointer to the xf86Monitor structure
+ which contains all information retrieved by DDC.
+ NULL will be returned on failure.
+
+ DDC2 Support
+
+ To read out DDC2 information I2C has to be initialized first.
+ (See documentation for the i2c module).
+ The function
+
+ xf86MonPtr xf86DoEDID_DDC2(int scrnIndex, I2CBusPtr pBus)
+
+ is provided to read out and process DDC2 data. A pointer
+ to the I2CBusRec of the appropriate I2C Bus has to be passed
+ as the second argument.
+ The function will return a pointer to the xf86Monitor structure
+ which contains all information retrieved by DDC.
+ NULL will be returned on failure.
+
+ Printing monitor parameters
+
+ To print out the information contained in the xf86Monitor
+ structure the function
+
+ xf86MonPtr xf86PrintEDID(xf86MonPtr monitor)
+
+ is provided.
+
+ Further processing of the xf86Monitor structure is not yet
+ implemented. However, it is planned to use the information
+ about video modes, gamma values etc.
+ Therefore it is strongly recommended to read out DDC data
+ before any video mode processing is done.
+
+
+
+
+$XFree86: xc/programs/Xserver/hw/xfree86/ddc/DDC.HOWTO,v 1.2 1998/12/06 13:30:39 dawes Exp $