[PATCH 3/5] drm/tilcdc: fixing off by one errors found on analyzer

[Darren Etheridge]

When hooking up to an HDMI analyzer noticed some timings were
off by one.  Referring to the hardware technical reference manual
for the lcd controller some of the timing registers use 0 to
represent 1.  This patch addresses that issue.

Signed-off-by: Darren Etheridge <detheridge at ti.com>
---
 drivers/gpu/drm/tilcdc/tilcdc_crtc.c |   19 ++++++++++++-------
 1 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
index 05f2b14..4455a41 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
@@ -289,17 +289,22 @@ static int tilcdc_crtc_mode_set(struct drm_crtc *crtc,
 	reg = tilcdc_read(dev, LCDC_RASTER_TIMING_2_REG) & ~0x000fff00;
 	reg |= LCDC_AC_BIAS_FREQUENCY(info->ac_bias) |
 		LCDC_AC_BIAS_TRANSITIONS_PER_INT(info->ac_bias_intrpt);
+
+	/*
+	 * subtract one from hfp, hbp, hsw because the hardware uses
+	 * a value of 0 as 1
+	 */
 	if (priv->rev == 2) {
-		reg |= (hfp & 0x300) >> 8;
-		reg |= (hbp & 0x300) >> 4;
-		reg |= (hsw & 0x3c0) << 21;
+		reg |= ((hfp-1) & 0x300) >> 8;
+		reg |= ((hbp-1) & 0x300) >> 4;
+		reg |= ((hsw-1) & 0x3c0) << 21;
 	}
 	tilcdc_write(dev, LCDC_RASTER_TIMING_2_REG, reg);
 
 	reg = (((mode->hdisplay >> 4) - 1) << 4) |
-		((hbp & 0xff) << 24) |
-		((hfp & 0xff) << 16) |
-		((hsw & 0x3f) << 10);
+		(((hbp-1) & 0xff) << 24) |
+		(((hfp-1) & 0xff) << 16) |
+		(((hsw-1) & 0x3f) << 10);
 	if (priv->rev == 2)
 		reg |= (((mode->hdisplay >> 4) - 1) & 0x40) >> 3;
 	tilcdc_write(dev, LCDC_RASTER_TIMING_0_REG, reg);
@@ -307,7 +312,7 @@ static int tilcdc_crtc_mode_set(struct drm_crtc *crtc,
 	reg = ((mode->vdisplay - 1) & 0x3ff) |
 		((vbp & 0xff) << 24) |
 		((vfp & 0xff) << 16) |
-		((vsw & 0x3f) << 10);
+		(((vsw-1) & 0x3f) << 10);
 	tilcdc_write(dev, LCDC_RASTER_TIMING_1_REG, reg);
 
 	/*
-- 
1.7.0.4