[tx09linux] LCD videoparams changed

Simon Budig simon.budig at kernelconcepts.de
Wed Sep 7 14:54:44 UTC 2011

Hash: SHA1

On 09/07/2011 03:32 PM, Stephan Thamm wrote:
> I recently changed to a more recent revision of the kernel repository and am 
> having trouble with the LCD since then.
> The format of the videoparams environment variable seems to have changed. It 
> previously consisted of 3 parts and now needs 4 parts. The videoparams 
> calculator on the Kernel Concepts website still produces the old values.
> The code parsing the string is here:
> drivers/video/tmpa9xx-clcd.c:676
> Is this change intentional? How can I calculate a string of the new format?

It is an intentional change implemented by Michael. The main reasoning
behind it is to support "easy" shortcuts for common modes. You can use
"qvga", "wqvga", "vga" and "wvga" instead of the raw register values.
These are mainly designed for the glyn family displays, if you need
different values you need to fall back to the numbers. Or you extend
arch/arm/mach-tmpa9xx/baseboard*.c with new presets.

The display calculator on the site is unfortunately not yet updated.
Michael: If you still have the extended version somewhere, please send
it to me, so that I can incorporate it into the site.

Unfortunately I don't have a running tmpa-system available at the
moment, so I cannot verify this information. But the fourth value (IIRC
the LCDControl register) is pretty much static: Try 0x00010828 for a
16bit display.

Hope this helps,
- -- 
       Simon Budig                        kernel concepts GbR
       simon.budig at kernelconcepts.de      Sieghuetter Hauptweg 48
       +49-271-771091-17                  D-57072 Siegen

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