Shifted framebuffer after X11 starts on mx28

[Marek Vasut]

Dear Fabio Estevam,

> Hi,
> 
> I am running 3.8.2 kernel on a mx28evk and when I start X11 I get a
> "shifted" framebuffer.
> 
> The framebuffer works well if X11 is not called.
> 
> There is no issue with X11 when running with Freescale  2.6.35 kernel.
> 
> Looking at drivers/video/mxsfb.c there is the following comment:
> 
> 	/*
> 	 * It seems, you can't re-program the controller if it is still running.
> 	 * This may lead into shifted pictures (FIFO issue?).
> 	 * So, first stop the controller and drain its FIFOs
> 	 */
> 
> So, it looks like that I am still facing this issue when X11 starts.
> 
> If anyone has any suggestions, please let me know.

This is not it, I almost hunted the bug down. Hang on.

Basically check mxsfb_set_par() and observe fb_info->var.sync . It's set to 
"something" during regular framebuffer operation and it's set to "something 
else" during Xorg operation. And that's what causes it to get broken. I forced 
fb_info->var.sync to the "something" value by hardcoding it in kernel just now 
for a quick test and X works for me.

Best regards,
Marek Vasut