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From 7db3721cba9538a928b31e81a4663e5688c228b1 Mon Sep 17 00:00:00 2001
From: Harigovindan P <harigovi@codeaurora.org>
Date: Tue, 7 Jan 2020 11:10:08 +0530
Subject: drm/msm: update LANE_CTRL register value from default value
Git-commit: e3ff68812384dd7f219b331535ede94b0974d5a7
Patch-mainline: v5.6-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322

LANE_CTRL register in latest version of DSI controller (v2.2)
has additional functionality introduced to enable/disable HS
signalling with default value set to enabled. To accommodate this
change, LANE_CTRL register should be read and bit wise ORed to enable
non continuous clock mode. Without this change, if register is written
directly, HS signalling will be disabled resulting in black screen.

Changes in v1:
	-Update LANE_CTRL register value
Changes in v2:
	-Changing commit message accordingly.

Signed-off-by: Harigovindan P <harigovi@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/msm/dsi/dsi_host.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
index 33c8d6dac5a9..11ae5b8444c3 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -833,7 +833,7 @@ static void dsi_ctrl_config(struct msm_dsi_host *msm_host, bool enable,
 	u32 flags = msm_host->mode_flags;
 	enum mipi_dsi_pixel_format mipi_fmt = msm_host->format;
 	const struct msm_dsi_cfg_handler *cfg_hnd = msm_host->cfg_hnd;
-	u32 data = 0;
+	u32 data = 0, lane_ctrl = 0;
 
 	if (!enable) {
 		dsi_write(msm_host, REG_DSI_CTRL, 0);
@@ -921,9 +921,11 @@ static void dsi_ctrl_config(struct msm_dsi_host *msm_host, bool enable,
 	dsi_write(msm_host, REG_DSI_LANE_SWAP_CTRL,
 		  DSI_LANE_SWAP_CTRL_DLN_SWAP_SEL(msm_host->dlane_swap));
 
-	if (!(flags & MIPI_DSI_CLOCK_NON_CONTINUOUS))
+	if (!(flags & MIPI_DSI_CLOCK_NON_CONTINUOUS)) {
+		lane_ctrl = dsi_read(msm_host, REG_DSI_LANE_CTRL);
 		dsi_write(msm_host, REG_DSI_LANE_CTRL,
-			DSI_LANE_CTRL_CLKLN_HS_FORCE_REQUEST);
+			lane_ctrl | DSI_LANE_CTRL_CLKLN_HS_FORCE_REQUEST);
+	}
 
 	data |= DSI_CTRL_ENABLE;
 
-- 
2.28.0