[PATCH v4 12/17] drm/bridge: cdns-dsi: Adjust mode to negative syncs

[Tomi Valkeinen]

The Cadence DSI requires negative syncs from the incoming video signal,
but at the moment that requirement is not expressed in any way. If the
crtc decides to use positive syncs, things break down.

Use the adjusted_mode in atomic_check to set the sync flags to negative
ones.

Reviewed-by: Aradhya Bhatia <aradhya.bhatia at linux.dev>
Tested-by: Parth Pancholi <parth.pancholi at toradex.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen at ideasonboard.com>
---
 drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
index f7d7d277367e..d49b4789a074 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
@@ -908,9 +908,13 @@ static int cdns_dsi_bridge_atomic_check(struct drm_bridge *bridge,
 	struct cdns_dsi_input *input = bridge_to_cdns_dsi_input(bridge);
 	struct cdns_dsi *dsi = input_to_dsi(input);
 	struct cdns_dsi_bridge_state *dsi_state = to_cdns_dsi_bridge_state(bridge_state);
-	const struct drm_display_mode *adjusted_mode = &crtc_state->adjusted_mode;
+	struct drm_display_mode *adjusted_mode = &crtc_state->adjusted_mode;
 	struct cdns_dsi_cfg *dsi_cfg = &dsi_state->dsi_cfg;
 
+	/* cdns-dsi requires negative syncs */
+	adjusted_mode->flags &= ~(DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
+	adjusted_mode->flags |= DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC;
+
 	return cdns_dsi_check_conf(dsi, adjusted_mode, dsi_cfg);
 }
 

-- 
2.43.0