[BUGFIX PATCH] video: mxsfb: fix crash when unblanking the display

[Shawn Guo]

On Fri, Jan 04, 2013 at 09:08:12AM +0200, Lauri Hintsala wrote:
> On 11/29/2012 01:55 PM, Lothar Waßmann wrote:
> >Hi,
> >
> >adding Juergen Beisert as the driver's author to the recipient list.
> >
> >Lothar Waßmann writes:
> >>The VDCTRL4 register does not provide the MXS SET/CLR/TOGGLE feature.
> >>The write in mxsfb_disable_controller() sets the data_cnt for the LCD
> >>DMA to 0 which obviously means the max. count for the LCD DMA and
> >>leads to overwriting arbitrary memory when the display is unblanked.
> >>
> >>Note: I already sent this patch in December 2011 but noone picked it up obviously.
> >>
> >>Signed-off-by: Lothar Waßmann <LW at KARO-electronics.de>
> 
> Tested-by: Lauri Hintsala <lauri.hintsala at bluegiga.net>
> 
> This fixes the CPU freezing. I really recommend to apply this patch
> into mainline soon because unblanking freezes the whole system!!!
> 
> Default value of consoleblank parameter is 600 seconds and the whole
> system crashes every time when framebuffer console is activated
> after that timeout. I wonder why this issue is still open in
> mainline kernel.

Part of the reason is the FB maintainer's absence.  Let me try to send
it through arm-soc tree.

> 
> Should this patch be added into stable versions too?
> 
Yes, will do.

Shawn