[PATCH] drm/bridge: tc358767: Support input format negotiation hook

[Aradhya Bhatia <a-bhatia1@ti.com>]

With new connector model, tc358767 will not create the connector, when
DRM_BRIDGE_ATTACH_NO_CONNECTOR is set and display-controller driver will
rely on format negotiation to setup the encoder format.

Add the missing input-format negotiation hook in the
drm_bridge_funcs to complete DRM_BRIDGE_ATTACH_NO_CONNECTOR support.

Input format is selected to MEDIA_BUS_FMT_RGB888_1X24 as default, as is
the case with older model.

Reported-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Aradhya Bhatia <a-bhatia1@ti.com>
---

Notes:

  * Since I do not have hardware with me, this was just build tested. I would
    appreciate it if someone could test and review it, especically somebody, who
    uses the bridge for DPI/DSI to eDP format conversion.

  * The Toshiba TC358767 bridge is not enabled in arm64 defconfig by default,
    when it should be. Hence, I sent a quick patch[0] earlier.

[0]: https://lore.kernel.org/all/20231030152834.18450-1-a-bhatia1@ti.com/

 drivers/gpu/drm/bridge/tc358767.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
index ef2e373606ba..0affcefdeb1c 100644
--- a/drivers/gpu/drm/bridge/tc358767.c
+++ b/drivers/gpu/drm/bridge/tc358767.c
@@ -1751,6 +1751,30 @@ tc_dpi_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
 	return input_fmts;
 }
 
+static u32 *
+tc_edp_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;
+
+	*num_input_fmts = 0;
+
+	input_fmts = kcalloc(MAX_INPUT_SEL_FORMATS, sizeof(*input_fmts),
+			     GFP_KERNEL);
+	if (!input_fmts)
+		return NULL;
+
+	/* This is the DSI/DPI-end bus format */
+	input_fmts[0] = MEDIA_BUS_FMT_RGB888_1X24;
+	*num_input_fmts = 1;
+
+	return input_fmts;
+}
+
 static const struct drm_bridge_funcs tc_dpi_bridge_funcs = {
 	.attach = tc_dpi_bridge_attach,
 	.mode_valid = tc_dpi_mode_valid,
@@ -1777,6 +1801,7 @@ static const struct drm_bridge_funcs tc_edp_bridge_funcs = {
 	.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
 	.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
 	.atomic_reset = drm_atomic_helper_bridge_reset,
+	.atomic_get_input_bus_fmts = tc_edp_atomic_get_input_bus_fmts,
 };
 
 static bool tc_readable_reg(struct device *dev, unsigned int reg)

base-commit: c503e3eec382ac708ee7adf874add37b77c5d312
-- 
2.42.0