Adding new DVI resolutions
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How to Add new DVI resolutions to PSP OMAP releases
- How to add new DVI resolution to PSP1.0.x releases
- How to add new DVI resolution to PSP02.0x.0x(GIT) releases.
- How to add new DVI resolution to PSP03.0x.0x(GIT) releases.
Required parameters in DSS for adding new resolution.
- Following are the important parameters that needs to be configured in DSS for adding the new resolution.
- Height and Width of the resolution.
- Pixel clock required to support that resolution.
- Timing parameters
- Horizontal front porch
- Horizontal Sync Length.
- Horizontal back porch.
- Vertical Front porch.
- Vertical Sync Length.
- Vertical back porch.
- Further information on timing parameters can be found at
How to get the standard parameters for Different resolutions.
- Timing parameters for the various standard resolutions can be found at the video timing calculator website below.
- Parameters given by Video timing calculator for XGA resolution
- Width = 1024 pixels
- Height = 768 pixels
- clock rate = 65Mhz.
- hfp = 24 pixels.
- hbp = 160 pixels.
- hsw = 136 pixels.
- vfp = 3 lines.
- vbp = 29 lines.
- vsw = 6 lines.
- Width = 1024 pixels
- Parameters given by Video timing calculator for SVGA resolution
- Width = 800pixels
- Height = 600 pixels
- clock rate = 40 Mhz.
- hfp = 40 pixels.
- hbp = 88 pixels.
- hsw = 128 pixels.
- vfp = 1 lines.
- vbp = 23 lines.
- vsw = 4 lines.
- Width = 800pixels
Add new DVI resolution in PSP1.0.x release XGA resolution.
- arch/arm/plat-omap/display.c contains the parameter structure for adding new resolutions.
- Above file already contains the parameters for 720P and 480P resolution.
- Search for 720P string in arch/arm/plat-omap/display.c file.
- you can see the dvi_modes array of type struct omap35x_mode_info with entry for 720P and 480P resolutiojn.
- structure omap35x_mode_info has the required fields for setting timing parameters for the new DVI resolution.
- Add new entry to the "dvi_modes" array with all the above fields populated as given by the video timing calculator.
- Compile the kernel.
- switch the ch0_output to DVI,
- switch the ch0_mode to XGA.
- XGA resolution is added.
Add new DVI resolution in PSP02.0.x release SVGA resolution.
- In PSP2.0.x new DVI resolution can be added during run time using the sysfs entry.
- The sysfs entry is "/sys/devices/platform/omapfb/displays"
- Input to the sysfs entry is in the following format.
- echo > "<display_device> h:<xres/hfp/hbp/hsw> v:<yres/vfp/vbp/vsw> p:<pixel_clock>" > /sys/devices/platform/omapfb/displays
- where <display_device> will be DVI or TV or LCD,
- h: is for configuring the various horizontal timing parameters like horizontal resolution, horizontal front porch, horizontal back porch and horizontal sync length.
- v: is for configuring the various vertical timing parameters like vertical resolution, vertical front porch, vertical back porch and vertical sync length.
- echo > "<display_device> h:<xres/hfp/hbp/hsw> v:<yres/vfp/vbp/vsw> p:<pixel_clock>" > /sys/devices/platform/omapfb/displays
- We just need to program the right parameters to the sysfs entries to get any desired DVI resolution. We just got the correct timing parameters in the slide from the video timing calculator website
- For the SVGA resolution input to sysfs entry will be
- echo "dvi h:800/40/88/63 v:600/1/23/4 p:40000" > /sys/devices/platform/omapfb/displays
- For XGA resolution input to the sysfs entry will be like.
- echo "dvi h:1024/24/160/63 v:768/3/29/6 p:65000" > /sys/devices/platform/omapfb/displays
- Please note that once the resolution is changed both on the V4L2 driver and FBDEV driver you need to again progrm various pipeline specific parameters like
- For frame buffer xres, yres, yres_virtual, xres_virtual.
- For V4L2 driver widh, height
Add new DVI resolution in PSP03.00.x releases: 720P resolution.
- In PSP03.00.x new DVI resolution can be added by two ways
- Using Boot Argument
- Run time using the sysfs entry.
Using Boot Argument
- Through Boot Arguments user can change/override the default resolution and respective timing parameters.
- command option is "omapfb.mode=<display_device>:<xres>x<yres>@<fps>"
- For 720P resolution the command line would be
# setenv bootargs console=ttyS0,115200n8 mem=128M noinitrd root=/dev/nfs nfsroot=nfs-server/home,nolock ip=dhcp omapfb.mode=dvi:1280x720@60
NOTE: Please make sure that the configured resolution is available in list of supported modes, also there are different methods to specify Fbdev mode options, please refer to
<kernel dir>/drivers/video/modedb.c.
Using the SYSFS entry
- The sysfs entry is "/sys/devices/platform/omapdss/display2/timings"
- Input to the sysfs entry is in the following format.
- echo "<pixel_clock>,<xres/hfp/hbp/hsw>,<yres/vfp/vbp/vsw>" > /sys/devices/platform/omapdss/display2/timings
- We just need to program the right parameters to the sysfs entries to get any desired DVI resolution. We just got the correct timing parameters in the slide from the video timing calculator website
- For the 720P resolution input to sysfs entry will be
# echo "72428,1280/190/120/32,720/13/3/5" > /sys/devices/platform/omapdss/display2/timings
- For XGA resolution input to the sysfs entry will be like.
# echo "65000,1024/24/160/63,768/3/29/6" > /sys/devices/platform/omapdss/display2/timings
- Please note that once the resolution is changed both on the V4L2 driver and FBDEV driver you need to again program various pipeline specific parameters like
- For frame buffer xres, yres, yres_virtual, xres_virtual.
- For V4L2 driver width, height
Recording and demo of the above content
| Sl.No | OMAP PSP Presentation | Duration (mins) | Description |
|---|---|---|---|
| 1 | OMAP PSP - Adding new DVI resolution to OMAP PSP release | 19 | Adding new DVI resolution to OMAP PSP release |
| For technical support on OMAP please post your questions on The OMAP Forum. Please post only comments about the article Adding new DVI resolutions here. |
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