Re: [PATCH v2 1/5] drm/bridge: nwl-dsi: Add atomic_get_input_bus_fmts

[Lucas Stach <l.stach@pengutronix.de>]

Am Montag, dem 04.10.2021 um 09:27 +0200 schrieb Guido Günther:
> Components further up in the chain might ask us for supported formats.
> 
> Without this MEDIA_BUS_FMT_FIXED is assumed which then breaks display
> output with mxsfb since it can't determine a proper bus format.
> 
> We handle the bus formats that correspond to the DSI formats the bridge
> can potentially output (see chapter 13.6 of the i.MX 8MQ reference
> manual) - which matches what xsfb can input.
> 
> Fixes: b776b0f00f24 ("drm: mxsfb: Use bus_format from the nearest bridge if present")
> 
> Signed-off-by: Guido Günther <agx@sigxcpu.org>

Reviewed-by: Lucas Stach <l.stach@pengutronix.de>

> ---
>  drivers/gpu/drm/bridge/nwl-dsi.c | 35 ++++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c
> index a251cc1f088f..27c80d36846b 100644
> --- a/drivers/gpu/drm/bridge/nwl-dsi.c
> +++ b/drivers/gpu/drm/bridge/nwl-dsi.c
> @@ -1234,6 +1234,40 @@ static void nwl_dsi_bridge_detach(struct drm_bridge *bridge)
>  	drm_of_panel_bridge_remove(dsi->dev->of_node, 1, 0);
>  }
>  
> +static u32 *nwl_bridge_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
> +						 struct drm_bridge_state *bridge_state,
> +						 struct drm_crtc_state *crtc_state,
> +						 struct drm_connector_state *conn_state,
> +						 u32 output_fmt,
> +						 unsigned int *num_input_fmts)
> +{
> +	u32 *input_fmts, input_fmt;
> +
> +	*num_input_fmts = 0;
> +
> +	switch (output_fmt) {
> +	/* If MEDIA_BUS_FMT_FIXED is tested, return default bus format */
> +	case MEDIA_BUS_FMT_FIXED:
> +		input_fmt = MEDIA_BUS_FMT_RGB888_1X24;
> +		break;
> +	case MEDIA_BUS_FMT_RGB888_1X24:
> +	case MEDIA_BUS_FMT_RGB666_1X18:
> +	case MEDIA_BUS_FMT_RGB565_1X16:
> +		input_fmt = output_fmt;
> +		break;
> +	default:
> +		return NULL;
> +	}
> +
> +	input_fmts = kcalloc(1, sizeof(*input_fmts), GFP_KERNEL);
> +	if (!input_fmts)
> +		return NULL;
> +	input_fmts[0] = input_fmt;
> +	*num_input_fmts = 1;
> +
> +	return input_fmts;
> +}
> +
>  static const struct drm_bridge_funcs nwl_dsi_bridge_funcs = {
>  	.atomic_duplicate_state	= drm_atomic_helper_bridge_duplicate_state,
>  	.atomic_destroy_state	= drm_atomic_helper_bridge_destroy_state,
> @@ -1241,6 +1275,7 @@ static const struct drm_bridge_funcs nwl_dsi_bridge_funcs = {
>  	.atomic_check		= nwl_dsi_bridge_atomic_check,
>  	.atomic_enable		= nwl_dsi_bridge_atomic_enable,
>  	.atomic_disable		= nwl_dsi_bridge_atomic_disable,
> +	.atomic_get_input_bus_fmts = nwl_bridge_atomic_get_input_bus_fmts,
>  	.mode_set		= nwl_dsi_bridge_mode_set,
>  	.mode_valid		= nwl_dsi_bridge_mode_valid,
>  	.attach			= nwl_dsi_bridge_attach,