Hello Stefan,
The issue is more low level. The problem is with the lvds converter, it is getting stuck.
There was a modification in the way that the clock (LCD_PCLK_WR) changes when uboot switches to linux image. In the version 2.4, there are a intermediate clock between uboot and linux image (uboot uses 26MHz, than there are a moment that the clock slows to 6.5Mhz, and then to the value set in the DTC, in my case, 33MHz. In version 2.6, looks like that the clocks just switches from 26MHz to 33MHz. In the first case (2.4 verion), the LVDS converter isn’t affected by the clock variation, but in 2.6 version, it stucks in the moment that the frequency varies. This is a problem that can happen and it is written in the datasheet of the DS90C393B (lvds converter from Texas).
A way to force the lvds converter to assumes the new clock, is toggling the powerdown line, in our case BL_ON, so the PLL of the chip will be reseted. I tested this using the commands listed bellow, and after that, the LCD display starts to work properly (looking at the lvds converter, its outputs starts to operate again).
echo 1 > /sys/class/backlight/backlight.17/bl_power
echo 0 > /sys/class/backlight/backlight.17/bl_power
The question is, there is a way to toggle BL_ON line after the kernel assert the frequency from panel-simple.c?