Hi,
On 02/26/2015 10:15 PM, Dr. H. Nikolaus Schaller wrote:
Hi, finally I succeeded in flashing the first panel controller.
The reason why we need that is that the BOE panels come unprogrammed.
Which means that we have to send a specific programming sequence through DCS/generic packets to the panel or it would not set up its gamma curves, and some other internal things.
The most noticeable effect of an unprogrammed panel controller is a vertical flickering stripe in the middle of the panel (which is better than with other panels which don’t show anything with unprogrammed controller).
Although I had already added that to our panel driver [1] and it works, we have a problem as soon as we want to operate the panel behind the rotator chip. The SSD2858 has a very unfortunate limitation that prohibits us sending the panel controller setup through the rotator.
*sigh* I wish it just had a pin for the passthrough mode, which we could connect to OMAP's GPIO.
The easiest solution appears to be to program the NVRAM/OTP default values of the panel controller. So that we simply do not have to send any programming command through the ssd chip.
This is what I have now set up. I use the omap5-panel interface board with bridged ssd chip. And I have added a DC/DC converter to produce 7.5V programming voltage plus a transistor which can be controlled by a spare gpio signal. This allows to program the controller through the MIPI interface and issue a “NVRAM write” command to copy the setup to NVRAM.
For the code [2], I use the panel-mipi-debug driver where a shell script can control almost everything of the MIPI interface (reset line, power, video stream, send/receive DCS and generic packets).
Anyways, this is only of temporary need. ED already has a batch of unprogrammed panels, while for series production he was promised to get them programmed at the factory.
Unfortunately this whole setup brings back bad memories of what we have with pandora nubs, where the microcontrollers are only readable and not programmable. If OMAP could reflash the micros, we could have updated them after release, and maybe it would made sense to start an reverse engineering project to create alternative firmware. As it is now absolutely nothing can be done to improve the nubs on pandora.
It's not good if we won't be able to program the panel, like updating gamma curves, something we already do on pandora. Or is that just for the init sequence that has problems?
Grazvydas