How to change the color depth on Beagle board or OMAP35xx EVM

We'd like to use 24 bit depth to run our application.But it seems
16bit depth is the default value when the board is powered off. How to
change the color depth on Beagle board or OMAP35xx EVM? Can anyone
help us? Thanks!

You cannot go to 24 bits unless you use the DVI output. The LCD will not support 24bits.

Gerald

Do you mean the LCD on OMAP35xx EVM at most supports 16bit depth? If
not, how does it support 32bit depth?
Thanks!

The cause is for the kernel or for the device(LCD)?
Thanks!

The LCD is 18bits. The DVI is 24 bit which is the maximum the OMAP3 can output on the LCD interface.

Gerald

So it is impossible to show a application in true color, isn't it?

Correct. Feel free to read up on the capabilities of the OMAP3530 at http://focus.ti.com/docs/prod/folders/print/omap3530.html .

Gerald

The following is the description of Display subsystem of OMAP3530:
Display Subsystem
Parallel Digital Output
Up to 24-Bit RGB
HD Maximum Resolution
Supports Up to 2 LCD Panels
Support for Remote Frame Buffer Interface (RFBI) LCD Panels
2 10-Bit Digital-to-Analog Converters (DACs) Supporting:
Composite NTSC/PAL Video
Luma/Chroma Separate Video (S-Video)
Rotation 90-, 180-, and 270-degrees
Resize Images From 1/4x to 8x
Color Space Converter
8-bit Alpha Blending

From this we can see it supports 24-Bit RGB output. And I have checked
the specification of the LCD of OMAP35xx EVM and found this LCD
supports 24-Bit RGB. So my question is how to change the color depth
from 16bit to 24bit?Do we need to modify kernel?
Thanks!

The LCD on the EVM only supports 18 bits. The reason I know this is because I designed it. The DVI port is the only port that can provice 24 bit color.

Gerald

That is such a HUGE bummer! I was really hoping to drive larger panels in all their glory.
Was this decision a board space issue?

-Glen

No. The OMAP3530 only has 24 bits out. It is the way the chip was desinged, not becaiuse of board space. The LCD only has 18 bits into so, we could not attach all 24.

Gerald

So the LCD breakout was designed to only support the same LCD used on the EVM?

The EVM was designed to support the LCD on the EVM, all 18 bits. The expansion connector on the EVM has all 24 bits accessible. So, if you want to create another board that supports an LCD panel that can use all 24 bits, then you can by connecting it to the expansion headers on the EVM.

Gerald