[PATCH v10 11/69] drm/display: hdmi: Advertise SCDC source version when scrambling

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.

Acked-by: Maxime Ripard <[email protected]>
Tested-by: Maud Spierings <[email protected]>
Tested-by: Diederik de Haas <[email protected]>  # NanoPC-T6 LTS, Rock 5B
Signed-off-by: Cristian Ciocaltea <[email protected]>
---
 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 cfecfef639ad..493f2728ab86 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)
@@ -556,6 +557,12 @@ int drm_connector_hdmi_enable_scrambling(struct drm_connector *connector,
 	if (!connector->ddc)
 		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");
 
 	if (!hdmi->scdc_work_initialized) {

-- 
2.55.0