[PATCH 5.15 720/917] drm/bridge: nwl-dsi: Add atomic_get_input_bus_fmts

[Greg Kroah-Hartman]

From: Guido Günther <agx@xxxxxxxxxxx>

[ Upstream commit 2f1495fac8d38bfade18bd7e31fa787cd7815626 ]

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@xxxxxxxxxxx>
Reviewed-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
Reviewed-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/1712f2b952694fd4484dfd8576fbc5b4d7adf042.1633959458.git.agx@xxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 ed8ac5059cd26..a7389a0facfb4 100644
--- 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,
-- 
2.33.0