[PATCH v3 3/6] drm/bridge: mhdp8546: Add minimal format negotiation

[Nikhil Devshatwar <nikhil.nd@ti.com>]

With new connector model, mhdp bridge will not create the connector and
SoC driver will rely on format negotiation to setup the encoder format.

Support minimal format negotiations hooks in the drm_bridge_funcs.
Complete format negotiation can be added based on EDID data.
This patch adds the minimal required support to avoid failure
after moving to new connector model.

Signed-off-by: Nikhil Devshatwar <nikhil.nd@ti.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
---

Notes:
    changes from v1:
    * cosmetic fixes, commit message update

 .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index d0c65610ebb5..2cd809eed827 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -2078,6 +2078,30 @@ cdns_mhdp_bridge_atomic_reset(struct drm_bridge *bridge)
 	return &cdns_mhdp_state->base;
 }
 
+static u32 *cdns_mhdp_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;
+	u32 default_bus_format = MEDIA_BUS_FMT_RGB121212_1X36;
+
+	*num_input_fmts = 0;
+
+	if (output_fmt != MEDIA_BUS_FMT_FIXED)
+		return NULL;
+
+	input_fmts = kzalloc(sizeof(*input_fmts), GFP_KERNEL);
+	if (!input_fmts)
+		return NULL;
+
+	*num_input_fmts = 1;
+	input_fmts[0] = default_bus_format;
+	return input_fmts;
+}
+
 static int cdns_mhdp_atomic_check(struct drm_bridge *bridge,
 				  struct drm_bridge_state *bridge_state,
 				  struct drm_crtc_state *crtc_state,
@@ -2142,6 +2166,7 @@ static const struct drm_bridge_funcs cdns_mhdp_bridge_funcs = {
 	.atomic_duplicate_state = cdns_mhdp_bridge_atomic_duplicate_state,
 	.atomic_destroy_state = cdns_mhdp_bridge_atomic_destroy_state,
 	.atomic_reset = cdns_mhdp_bridge_atomic_reset,
+	.atomic_get_input_bus_fmts = cdns_mhdp_get_input_bus_fmts,
 	.detect = cdns_mhdp_bridge_detect,
 	.get_edid = cdns_mhdp_bridge_get_edid,
 	.hpd_enable = cdns_mhdp_bridge_hpd_enable,
-- 
2.17.1

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