[PATCH v4 1/2] drm: bridge: ti-sn65dsi83: Remove NO_HFP and NO_HBP mode flags for LVDS stability

[Sudarshan Shetty]

The current DSI mode configuration disables horizontal front porch
(HFP) and back porch (HBP) transmission using
MIPI_DSI_MODE_VIDEO_NO_HFP and MIPI_DSI_MODE_VIDEO_NO_HBP.

However, the SN65DSI83/84 bridge relies on receiving full horizontal
timing information over DSI in order to correctly reconstruct the
LVDS output timings. When HFP and HBP are not transmitted, the bridge
cannot recreate the required timing parameters, resulting in unstable
or missing display output on some panels.

The SN65DSI84 datasheet also describes transmission of complete
horizontal timing information as part of the DSI video stream.

Remove MIPI_DSI_MODE_VIDEO_NO_HFP and MIPI_DSI_MODE_VIDEO_NO_HBP
so that HFP and HBP timing information is transmitted to the bridge.

Reference:
SN65DSI84 Datasheet, Section 7.4.7 (page 20):
https://www.ti.com/lit/ds/symlink/sn65dsi84.pdf?ts=1776924088430&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FSN65DSI84

Tested-by: Luca Ceresoli <luca.ceresoli@xxxxxxxxxxx>
Tested-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
Signed-off-by: Sudarshan Shetty <tessolveupstream@xxxxxxxxx>
---
 drivers/gpu/drm/bridge/ti-sn65dsi83.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
index 42b451432bbb..c03ff1ea9df8 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
@@ -977,7 +977,6 @@ static int sn65dsi83_host_attach(struct sn65dsi83 *ctx)
 	dsi->lanes = dsi_lanes;
 	dsi->format = MIPI_DSI_FMT_RGB888;
 	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
-			  MIPI_DSI_MODE_VIDEO_NO_HFP | MIPI_DSI_MODE_VIDEO_NO_HBP |
 			  MIPI_DSI_MODE_VIDEO_NO_HSA | MIPI_DSI_MODE_NO_EOT_PACKET;
 
 	ret = devm_mipi_dsi_attach(dev, dsi);
-- 
2.34.1