[PATCH v2 1/4] drm/rockchip: lvds: propagate bus_flags to the CRTC state

[Rok Markovic <rok@kanardia.eu>]

rockchip_lvds_encoder_atomic_check() sets output_mode and output_type
but never copies the connector's bus_flags into the Rockchip CRTC
state, unlike dw_dp-rockchip.c and dw-mipi-dsi2-rockchip.c which both
do.

panel-lvds parses pixelclk-active from the DT display timing and
publishes it on the connector as DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE.
VOP2 reads that flag back out of the CRTC state to decide
POLFLAG_DCLK_INV. With the flag dropped here, vcstate->bus_flags is
always zero, so a panel that asks to be clocked on the falling edge is
driven on the rising one, and there is no way to express the panel's
requirement from DT at all.

No functional change for the SoCs currently supported by this driver:
rk3288 and px30 pair with the VOP1 driver (rockchip_drm_vop.c), which
never reads bus_flags - only VOP2 consumes it. The flag becomes live
with the RK3568 support added later in this series.

Signed-off-by: Rok Markovic <rok@kanardia.eu>
Assisted-by: Claude:claude-opus-4-8
---
No changes since v1.

 drivers/gpu/drm/rockchip/rockchip_lvds.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_lvds.c b/drivers/gpu/drm/rockchip/rockchip_lvds.c
index 75f898a..95fa0a9 100644
--- a/drivers/gpu/drm/rockchip/rockchip_lvds.c
+++ b/drivers/gpu/drm/rockchip/rockchip_lvds.c
@@ -129,7 +129,15 @@ rockchip_lvds_encoder_atomic_check(struct drm_encoder *encoder,
 				   struct drm_connector_state *conn_state)
 {
 	struct rockchip_crtc_state *s = to_rockchip_crtc_state(crtc_state);
-
+	struct drm_connector *connector = conn_state->connector;
+
+	/*
+	 * The VOP derives the pixel clock polarity from this. Without it a
+	 * panel that declares pixelclk-active = <0> is clocked on the wrong
+	 * edge. panel-lvds fills the connector's bus_flags in from the DT
+	 * display timing.
+	 */
+	s->bus_flags = connector->display_info.bus_flags;
 	s->output_mode = ROCKCHIP_OUT_MODE_P888;
 	s->output_type = DRM_MODE_CONNECTOR_LVDS;
 
-- 
2.43.0