atmel_lcd: Allow contrast polarity to be either positive or negative

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>

drivers/video/atmel_lcdfb.c

diff --git a/drivers/video/atmel_lcdfb.c b/drivers/video/atmel_lcdfb.c
index db86763..c02ffd8 100644
--- a/drivers/video/atmel_lcdfb.c
+++ b/drivers/video/atmel_lcdfb.c
@@ -143,8 +143,9 @@
 
 	/* Set contrast */
 	value = ATMEL_LCDC_PS_DIV8 |
-		ATMEL_LCDC_POL_POSITIVE |
 		ATMEL_LCDC_ENA_PWMENABLE;
+	if (!panel_info.vl_cont_pol_low)
+		value |= ATMEL_LCDC_POL_POSITIVE;
 	lcdc_writel(panel_info.mmio, ATMEL_LCDC_CONTRAST_CTR, value);
 	lcdc_writel(panel_info.mmio, ATMEL_LCDC_CONTRAST_VAL, ATMEL_LCDC_CVAL_DEFAULT);
 

include/lcd.h

diff --git a/include/lcd.h b/include/lcd.h
index cd9d49d..0e098d9 100644
--- a/include/lcd.h
+++ b/include/lcd.h
@@ -167,6 +167,7 @@
 	u_long vl_sync;		/* Horizontal / vertical sync */
 	u_long vl_bpix;		/* Bits per pixel, 0 = 1, 1 = 2, 2 = 4, 3 = 8, 4 = 16 */
 	u_long vl_tft;		/* 0 = passive, 1 = TFT */
+	u_long vl_cont_pol_low;	/* contrast polarity is low */
 
 	/* Horizontal control register. */
 	u_long vl_hsync_len;	/* Length of horizontal sync */