linux-kernel - [PATCH 1/4] drm/bridge: lt8912b: add vsync hsync

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Date:   Thu, 22 Sep 2022 14:43:03 +0200
From:   Philippe Schenker <dev@...henker.ch>
To:     dri-devel@...ts.freedesktop.org,
        Adrien Grassein <adrien.grassein@...il.com>
Cc:     Jernej Skrabec <jernej.skrabec@...il.com>,
        Jonas Karlman <jonas@...boo.se>,
        Robert Foss <robert.foss@...aro.org>,
        linux-kernel@...r.kernel.org, Daniel Vetter <daniel@...ll.ch>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Philippe Schenker <philippe.schenker@...adex.com>
Subject: [PATCH 1/4] drm/bridge: lt8912b: add vsync hsync

From: Philippe Schenker <philippe.schenker@...adex.com>

Currently the bridge driver does not take care whether or not the display
needs positive/negative vertical/horizontal syncs. Pass these two flags
to the bridge from the EDID that was read out from the display.

Fixes: 30e2ae943c26 ("drm/bridge: Introduce LT8912B DSI to HDMI bridge")
Signed-off-by: Philippe Schenker <philippe.schenker@...adex.com>

---

 drivers/gpu/drm/bridge/lontium-lt8912b.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/lontium-lt8912b.c b/drivers/gpu/drm/bridge/lontium-lt8912b.c
index 28bad30dc4e5..0fd3472e767c 100644
--- a/drivers/gpu/drm/bridge/lontium-lt8912b.c
+++ b/drivers/gpu/drm/bridge/lontium-lt8912b.c
@@ -268,7 +268,7 @@ static int lt8912_video_setup(struct lt8912 *lt)
 	u32 hactive, h_total, hpw, hfp, hbp;
 	u32 vactive, v_total, vpw, vfp, vbp;
 	u8 settle = 0x08;
-	int ret;
+	int ret, hsync_activehigh, vsync_activehigh;
 
 	if (!lt)
 		return -EINVAL;
@@ -278,12 +278,14 @@ static int lt8912_video_setup(struct lt8912 *lt)
 	hpw = lt->mode.hsync_len;
 	hbp = lt->mode.hback_porch;
 	h_total = hactive + hfp + hpw + hbp;
+	hsync_activehigh = lt->mode.flags & DISPLAY_FLAGS_HSYNC_HIGH;
 
 	vactive = lt->mode.vactive;
 	vfp = lt->mode.vfront_porch;
 	vpw = lt->mode.vsync_len;
 	vbp = lt->mode.vback_porch;
 	v_total = vactive + vfp + vpw + vbp;
+	vsync_activehigh = lt->mode.flags & DISPLAY_FLAGS_VSYNC_HIGH;
 
 	if (vactive <= 600)
 		settle = 0x04;
@@ -317,6 +319,11 @@ static int lt8912_video_setup(struct lt8912 *lt)
 	ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x3e, hfp & 0xff);
 	ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x3f, hfp >> 8);
 
+	ret |= regmap_update_bits(lt->regmap[I2C_MAIN], 0xab, BIT(0),
+				  vsync_activehigh ? BIT(0) : 0);
+	ret |= regmap_update_bits(lt->regmap[I2C_MAIN], 0xab, BIT(1),
+				  hsync_activehigh ? BIT(1) : 0);
+
 	return ret;
 }
 
-- 
2.37.3