[PATCH v3 02/17] drm/bridge: Verify lane assignment is going to work during atomic_check

[Stephen Boyd]

Verify during drm_atomic_bridge_check() that the lane assignment set in
a bridge's atomic_check() callback is going to be satisfied by the
previous bridge. If the next bridge is requiring something besides the
default 1:1 lane assignment on its input then there must be an output
lane assignment on the previous bridge's output. Otherwise the next
bridge won't get the lanes assigned that it needs.

Cc: Andrzej Hajda <andrzej.hajda at intel.com>
Cc: Neil Armstrong <neil.armstrong at linaro.org>
Cc: Robert Foss <rfoss at kernel.org>
Cc: Laurent Pinchart <Laurent.pinchart at ideasonboard.com>
Cc: Jonas Karlman <jonas at kwiboo.se>
Cc: Jernej Skrabec <jernej.skrabec at gmail.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Maxime Ripard <mripard at kernel.org>
Cc: Thomas Zimmermann <tzimmermann at suse.de>
Cc: David Airlie <airlied at gmail.com>
Cc: Daniel Vetter <daniel at ffwll.ch>
Cc: <dri-devel at lists.freedesktop.org>
Cc: Pin-yen Lin <treapking at chromium.org>
Cc: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
Signed-off-by: Stephen Boyd <swboyd at chromium.org>
---
 drivers/gpu/drm/drm_bridge.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index bd18c1e91dee..68c7a321b9b3 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -860,6 +860,10 @@ static int drm_atomic_bridge_check(struct drm_bridge *bridge,
 				   struct drm_crtc_state *crtc_state,
 				   struct drm_connector_state *conn_state)
 {
+	u8 num_input_lanes, num_output_lanes = 0;
+	const struct drm_lane_cfg *input_lanes;
+	int i;
+
 	if (bridge->funcs->atomic_check) {
 		struct drm_bridge_state *bridge_state;
 		int ret;
@@ -873,12 +877,24 @@ static int drm_atomic_bridge_check(struct drm_bridge *bridge,
 						  crtc_state, conn_state);
 		if (ret)
 			return ret;
+		num_output_lanes = bridge_state->output_bus_cfg.num_lanes;
 	} else if (bridge->funcs->mode_fixup) {
 		if (!bridge->funcs->mode_fixup(bridge, &crtc_state->mode,
 					       &crtc_state->adjusted_mode))
 			return -EINVAL;
 	}
 
+	input_lanes = drm_bridge_next_bridge_lane_cfg(bridge,
+						      crtc_state->state,
+						      &num_input_lanes);
+	/*
+	 * Ensure this bridge is aware that the next bridge wants to
+	 * reassign lanes.
+	 */
+	for (i = 0; i < num_input_lanes; i++)
+		if (i != input_lanes[i].logical && !num_output_lanes)
+			return -ENOTSUPP;
+
 	return 0;
 }
 
-- 
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