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

[Chaoyi Chen <chaoyi.chen@rock-chips.com>]

On 7/17/2026 8:00 PM, Rok Markovic wrote:
> 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
> ---
>  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;
>  

Reviewed-by: Chaoyi Chen <chaoyi.chen@rock-chips.com>

-- 
Best, 
Chaoyi