[PATCH 4/5] drm/bridge: synopsys: dw-dp: Add HDR static metadata support

[Igor Paunovic <royalnet026@gmail.com>]

Send an HDR Metadata InfoFrame SDP (DP 1.4a, Table 2-100 and
Table 2-101) when the connector state carries HDR output metadata, and
attach the HDR_OUTPUT_METADATA property in the Rockchip glue so
userspace can set it.

The infoframe is built with drm_hdmi_infoframe_set_hdr_metadata() and
packed with drm_dp_hdr_metadata_infoframe_sdp_pack(), then written
into a free slot of the SDP register bank with vertical interval
transmission, so the controller resends it once per frame during the
vertical blanking period. The SDP is sent at the end of
dw_dp_video_enable(), next to the existing VSC SDP; the connector
state is passed down from atomic_enable(), which already looks it up.

The allocated slot is tracked in hdr_sdp_nr and released in
atomic_disable(), following the VSC SDP pattern exactly:
atomic_disable() only clears tracked slots, so an untracked slot would
leak on every enable/disable cycle until dw_dp_send_sdp() runs out of
free slots and fails with -EBUSY for every SDP, including VSC and
audio.

A metadata change on a live stream (HDR on/off toggle, different
mastering display data) forces a full modeset: atomic_check() compares
the old and new connector state with
drm_connector_atomic_hdr_metadata_equal() and sets
crtc_state->mode_changed, the same approach as dw-hdmi. The resulting
disable/enable cycle then drops or (re)sends the SDP.

Commits without HDR metadata are unaffected: with a NULL metadata blob
in both old and new connector state,
drm_connector_atomic_hdr_metadata_equal() treats them as equal, no
modeset is forced, and dw_dp_video_enable() skips the SDP. This keeps
plain SDR commits a no-op even for compositors that write a NULL blob
on every atomic modeset once the property exists (KWin does).

Signed-off-by: Igor Paunovic <royalnet026@gmail.com>
---
 drivers/gpu/drm/bridge/synopsys/dw-dp.c   | 44 +++++++++++++++++++++--
 drivers/gpu/drm/rockchip/dw_dp-rockchip.c |  2 ++
 2 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
index df149c52fce0..ca997ea53e66 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
@@ -24,6 +24,7 @@
 #include <drm/drm_bridge_connector.h>
 #include <drm/display/drm_dp_helper.h>
 #include <drm/display/drm_hdmi_audio_helper.h>
+#include <drm/display/drm_hdmi_helper.h>
 #include <drm/drm_edid.h>
 #include <drm/drm_of.h>
 #include <drm/drm_print.h>
@@ -369,6 +370,7 @@ struct dw_dp {
 	struct drm_bridge *next_bridge;
 
 	int vsc_sdp_nr;
+	int hdr_sdp_nr;
 	DECLARE_BITMAP(sdp_reg_bank, SDP_REG_BANK_SIZE);
 };
 
@@ -1171,6 +1173,28 @@ static int dw_dp_send_vsc_sdp(struct dw_dp *dp)
 	return dw_dp_send_sdp(dp, &sdp);
 }
 
+static int dw_dp_send_hdr_metadata_sdp(struct dw_dp *dp,
+				       const struct drm_connector_state *conn_state)
+{
+	struct hdmi_drm_infoframe frame;
+	struct dw_dp_sdp sdp = {};
+	ssize_t len;
+	int ret;
+
+	ret = drm_hdmi_infoframe_set_hdr_metadata(&frame, conn_state);
+	if (ret)
+		return ret;
+
+	len = drm_dp_hdr_metadata_infoframe_sdp_pack(dp->bridge.dev, &frame,
+						     &sdp.base, sizeof(sdp.base));
+	if (len < 0)
+		return len;
+
+	sdp.flags = DW_DP_SDP_VERTICAL_INTERVAL;
+
+	return dw_dp_send_sdp(dp, &sdp);
+}
+
 static int dw_dp_video_set_pixel_mode(struct dw_dp *dp)
 {
 	switch (dp->pixel_mode) {
@@ -1265,7 +1289,8 @@ static void dw_dp_video_disable(struct dw_dp *dp)
 			   FIELD_PREP(VIDEO_STREAM_ENABLE, 0));
 }
 
-static int dw_dp_video_enable(struct dw_dp *dp)
+static int dw_dp_video_enable(struct dw_dp *dp,
+			      const struct drm_connector_state *conn_state)
 {
 	struct dw_dp_link *link = &dp->link;
 	struct dw_dp_bridge_state *state;
@@ -1440,6 +1465,9 @@ static int dw_dp_video_enable(struct dw_dp *dp)
 	if (dw_dp_video_need_vsc_sdp(dp))
 		dp->vsc_sdp_nr = dw_dp_send_vsc_sdp(dp);
 
+	if (conn_state->hdr_output_metadata)
+		dp->hdr_sdp_nr = dw_dp_send_hdr_metadata_sdp(dp, conn_state);
+
 	return 0;
 }
 
@@ -1597,6 +1625,7 @@ static int dw_dp_bridge_atomic_check(struct drm_bridge *bridge,
 	struct dw_dp *dp = bridge_to_dp(bridge);
 	struct dw_dp_bridge_state *state;
 	const struct dw_dp_output_format *fmt;
+	struct drm_connector_state *old_conn_state;
 	struct drm_display_mode *mode;
 	int min_hbp = 16;
 	int min_hsync = 9;
@@ -1616,6 +1645,11 @@ static int dw_dp_bridge_atomic_check(struct drm_bridge *bridge,
 	state->bpc = fmt->bpc;
 	state->bpp = fmt->bpp;
 
+	old_conn_state = drm_atomic_get_old_connector_state(conn_state->state,
+							    conn_state->connector);
+	if (!drm_connector_atomic_hdr_metadata_equal(old_conn_state, conn_state))
+		crtc_state->mode_changed = true;
+
 	if ((adjusted_mode->hsync_start - adjusted_mode->hdisplay) & 0x1) {
 		adjusted_mode->hsync_start += 1;
 		dev_warn(dp->dev, "hfp is not 2 pixeel aligned, fixup to aligned hfp\n");
@@ -2016,7 +2050,7 @@ static void dw_dp_bridge_atomic_enable(struct drm_bridge *bridge,
 		return;
 	}
 
-	ret = dw_dp_video_enable(dp);
+	ret = dw_dp_video_enable(dp, conn_state);
 	if (ret < 0) {
 		dev_err(dp->dev, "failed to enable video: %d\n", ret);
 		return;
@@ -2066,6 +2100,11 @@ static void dw_dp_bridge_atomic_disable(struct drm_bridge *bridge,
 		dp->vsc_sdp_nr = -1;
 	}
 
+	if (dp->hdr_sdp_nr >= 0) {
+		dw_dp_clear_sdp(dp, dp->hdr_sdp_nr);
+		dp->hdr_sdp_nr = -1;
+	}
+
 	dw_dp_reset(dp);
 	pm_runtime_put_autosuspend(dp->dev);
 }
@@ -2668,6 +2707,7 @@ int dw_dp_probe(struct dw_dp *dp)
 		return ret;
 
 	dp->vsc_sdp_nr = -1;
+	dp->hdr_sdp_nr = -1;
 	dp->audio_interface = DW_DP_AUDIO_UNUSED;
 	dp->audio_sdp_nr = -1;
 
diff --git a/drivers/gpu/drm/rockchip/dw_dp-rockchip.c b/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
index 4dc29963b5d8..c5bc178c0a50 100644
--- a/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
@@ -198,6 +198,8 @@ static int dw_dp_rockchip_bind(struct device *dev, struct device *master, void *
 		return ret;
 	}
 
+	drm_connector_attach_hdr_output_metadata_property(connector);
+
 	return 0;
 }
 
-- 
2.43.0