From 2d81482821e9a825030cf4ba60de990f1a2bdfd0 Mon Sep 17 00:00:00 2001
From: Stefan Agner <stefan@agner.ch>
Date: Thu, 9 Nov 2017 18:09:30 +0100
Subject: [PATCH] video: fbdev: mxsfb: fix pixelclock polarity
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The PIXDATA flags of the display_flags enum are controller centric,
e.g. NEGEDGE means the controller shall drive the data signals on
pixelclocks negative edge. However, the drivers flag is display
centric: Sample the data on negative (falling) edge.

Therefore, change the if statement to check for the POSEDGE flag
(which is typically not set):
Drive on positive edge => sample on negative edge

Signed-off-by: Stefan Agner <stefan@agner.ch>
Acked-by: Shawn Guo <shawnguo@kernel.org>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Liu Ying <Ying.Liu@freescale.com>
Cc: Lothar Waßmann <LW@KARO-electronics.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Max Krummenacher <max.krummenacher@toradex.com>
Cc: Mauro Salvini <mauro.salvini@smigroup.net>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
---
 drivers/video/fbdev/mxsfb.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/mxsfb.c b/drivers/video/fbdev/mxsfb.c
index 7846f0e8bbbb..79b1dc7f042b 100644
--- a/drivers/video/fbdev/mxsfb.c
+++ b/drivers/video/fbdev/mxsfb.c
@@ -150,7 +150,7 @@
 #define STMLCDIF_24BIT 3 /** pixel data bus to the display is of 24 bit width */
 
 #define MXSFB_SYNC_DATA_ENABLE_HIGH_ACT	(1 << 6)
-#define MXSFB_SYNC_DOTCLK_FALLING_ACT	(1 << 7) /* negtive edge sampling */
+#define MXSFB_SYNC_DOTCLK_FALLING_ACT	(1 << 7) /* negative edge sampling */
 
 enum mxsfb_devtype {
 	MXSFB_V3,
@@ -788,7 +788,16 @@ static int mxsfb_init_fbinfo_dt(struct mxsfb_info *host,
 
 	if (vm.flags & DISPLAY_FLAGS_DE_HIGH)
 		host->sync |= MXSFB_SYNC_DATA_ENABLE_HIGH_ACT;
-	if (vm.flags & DISPLAY_FLAGS_PIXDATA_NEGEDGE)
+
+	/*
+	 * The PIXDATA flags of the display_flags enum are controller
+	 * centric, e.g. NEGEDGE means drive data on negative edge.
+	 * However, the drivers flag is display centric: Sample the
+	 * data on negative (falling) edge. Therefore, check for the
+	 * POSEDGE flag:
+	 * drive on positive edge => sample on negative edge
+	 */
+	if (vm.flags & DISPLAY_FLAGS_PIXDATA_POSEDGE)
 		host->sync |= MXSFB_SYNC_DOTCLK_FALLING_ACT;
 
 put_display_node: