video: mxsfb: fix crash when unblanking the display

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 Waßmann <LW@KARO-electronics.de>
Acked-by: Juergen Beisert <jbe@pengutronix.de>
Tested-by: Lauri Hintsala <lauri.hintsala@bluegiga.net>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/video/mxsfb.c b/drivers/video/mxsfb.c
index d837d63..03cb95a 100644 (file)
--- a/drivers/video/mxsfb.c
+++ b/drivers/video/mxsfb.c
@@ -366,7 +366,8 @@ static void mxsfb_disable_controller(struct fb_info *fb_info)
                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(host->clk);