From: Lothar Waßmann <LW@KARO-electronics.de>
Date: Thu, 22 Nov 2012 12:49:14 +0000 (+0100)
Subject: video: mxsfb: fix crash when unblanking the display
X-Git-Tag: firefly_0821_release~7541^2~140
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=fc65b0bb8b56913b0610588d83c78d0e5e968e9d;p=firefly-linux-kernel-4.4.55.git

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/video/mxsfb.c b/drivers/video/mxsfb.c
index 0b2f2dd41416..2f902900c80d 100644
--- a/drivers/video/mxsfb.c
+++ b/drivers/video/mxsfb.c
@@ -365,7 +365,8 @@ 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);