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Linux DaVinci Video Port Interface (VPIF)
Added by Terrence Lawrence about 12 years ago
I need to setup a VPIF interface (ala V4L2) using a Mity OMAP-L138F SoM platform running DaVinci Linux to support, BT.656, 8-bit, 720x480, composite (CVBS) video output only.
I have attempted to make customizations to the Linux kernel code in the board configuration module, board-mityomal138.c. Which derives from board-da850.c. I added software changes to perform the pin mux setup of the VPIF display pins, register the VPIF chip, the VPIF display device interface, and the video encoder chip.
Thus far, using TI’s ‘vpif_test_display’ application, and the V4L2 video stack. I have been able to successfully display color bars directly from the ADV7391 video encoder, to a analog display that’s connected to the SoM’s custom baseboard.
However, if I try to display a frame from memory using a known Y/C pattern. I get a blank screen. Connecting a scope to a few of the VPIF’s pins, such as CLKOUT2, DOUT7, and DOUT3. We were able to verify that the VPIF’s CLKOUT2 pin is putting out a 27 MHz clock. But pins DOUT3 and DOUT7 are flat lined at about 0V.
Replies (3)
RE: Linux DaVinci Video Port Interface (VPIF) - Added by Terrence Lawrence about 12 years ago
I am currently using MDK_2011-12-05 DaVinici Linux kernel to support VPIF on a OMAP-L138F SoM platform. I attempted to use the newer MDK, MDK_2012-08-10, and I noticed that the MDK_2012-08-10 DaVinici Linux kernel does not provide VPIF support for the OMAP-L138F SoM platform as a configuration option. Does anyone know why the VPIF support was removed from the MDK_2012-08-10 DaVinci Linux kernel version, and is not a kernel configurable option for the OMAL-L138F SoM platform?
RE: Linux DaVinci Video Port Interface (VPIF) - Added by Michael Williamson about 12 years ago
Hi Terrence,
Sorry for the confusion. The linux kernels 2.6.X tracked TI's Platform Support Package releases from their arago site, not the mainline. TI has the tendency to rewrite their git history on those PSP branches (as much of the code there was not submitted / accepted by the mainline) and as such it was nearly impossible to track their changes, mainline changes, and local changes made by Critical Link to support out SOMs. When we created newer 3.X branches, Critical Link decided to track the linux mainline (Linus' tree). Migrating to newer kernels is now feasible and has been done several times.
The VPIF support originally developed by TI for their platform support packages is still in the submission process to the mainline (targeted version appears to be 3.8). It has gone through a lot of revision since the 2.6.X PSP implementation as a result of the review from the mainline community. This is why you don't see it in the 3.2 kernel (ours, or the mainline).
We are planning to advance a new kernel branch when 3.8 is released. Until then you need to either use the 2.6 kernel or you'll need to merge in the bleeding edge changes from linus' tree (it should not be that hard as we are now tracking the mainline -- a merge would likely work or require very few conflict resolutions....).
Sorry.
-Mike
RE: Linux DaVinci Video Port Interface (VPIF) - Added by Terrence Lawrence about 12 years ago
My OMAP-L138 VPIF issue has been resolved! There was a conflict with PINMUX16 and PINMUX17 control register settings. The boards's LCD PINMUX settings were overriding the VPIF data out settings (i.e. disabling the VPIF DATAOUT[0-7] output). Needed to disable the LCD as a default configuration using the U-Boot bootloader application.
