[PATCH v8 08/39] drm/display: hdmi: Advertise SCDC source version when scrambling

[Cristian Ciocaltea]

The HDMI 2.0 spec advises that compliant Source devices report their
SCDC version in the Source Version register.  Do so when enabling
scrambling by calling drm_scdc_set_source_version().

Failures are non-fatal: SCDC version negotiation is purely informational
and does not gate scrambling or any high-bitrate functionality, so a
flaky DDC bus should not block scrambling setup.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea at collabora.com>
---
 drivers/gpu/drm/display/drm_hdmi_helper.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/display/drm_hdmi_helper.c b/drivers/gpu/drm/display/drm_hdmi_helper.c
index 7c96cccf683d..b8ed2a1e47f5 100644
--- a/drivers/gpu/drm/display/drm_hdmi_helper.c
+++ b/drivers/gpu/drm/display/drm_hdmi_helper.c
@@ -16,6 +16,7 @@
 #include <drm/drm_print.h>
 #include <drm/drm_property.h>
 
+#define DRM_HDMI_SCDC_SOURCE_VERSION	1
 #define DRM_HDMI_SCDC_POLL_DELAY_MS	1000
 
 static inline bool is_eotf_supported(u8 output_eotf, u8 sink_eotf)
@@ -531,6 +532,12 @@ int drm_connector_hdmi_enable_scrambling(struct drm_connector *connector,
 		return -EINVAL;
 	}
 
+	/*
+	 * Advertise our SCDC source version. This is purely informational and
+	 * does not gate scrambling, so failures are non-fatal.
+	 */
+	drm_scdc_set_source_version(connector, DRM_HDMI_SCDC_SOURCE_VERSION);
+
 	drm_dbg_kms(dev, "Enabling scrambling\n");
 
 	hdmi->scdc_cb = drm_scdc_monitor_scrambler;

-- 
2.54.0