[ 055/171] video: mxsfb: fix crash when unblanking the display

[Greg Kroah-Hartman]

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lothar WaÃmann <LW@xxxxxxxxxxxxxxxxxxx>

commit 6c1ecba8d84841277d68140ef485335d5be28485 upstream.

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.

Signed-off-by: Lothar WaÃmann <LW@xxxxxxxxxxxxxxxxxxx>
Acked-by: Juergen Beisert <jbe@xxxxxxxxxxxxxx>
Tested-by: Lauri Hintsala <lauri.hintsala@xxxxxxxxxxxx>
Signed-off-by: Shawn Guo <shawn.guo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/video/mxsfb.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/video/mxsfb.c
+++ b/drivers/video/mxsfb.c
@@ -366,7 +366,8 @@ static void mxsfb_disable_controller(str
 		loop--;
 	}
 
-	writel(VDCTRL4_SYNC_SIGNALS_ON, host->base + LCDC_VDCTRL4 + REG_CLR);
+	reg = readl(host->base + LCDC_VDCTRL4);
+	writel(reg & ~VDCTRL4_SYNC_SIGNALS_ON, host->base + LCDC_VDCTRL4);
 
 	clk_disable_unprepare(host->clk);
 


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