drm/bridge: nwl-dsi: Add atomic_get_input_bus_fmts

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>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1712f2b952694fd4484dfd8576fbc5b4d7adf042.1633959458.git.agx@sigxcpu.org

diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c
index ed8ac50..a7389a0 100644 (file)
--- a/drivers/gpu/drm/bridge/nwl-dsi.c
+++ b/drivers/gpu/drm/bridge/nwl-dsi.c
@@ -939,6 +939,40 @@ 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,
@@ -946,6 +980,7 @@ 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,