diff mbox series

[v11,11/74] drm/display: hdmi: Advertise SCDC source version when scrambling

Message ID 20260901-dw-hdmi-qp-scramb-v11-11-bc12954a0688@collabora.com (mailing list archive)
State New
Headers
Series Add HDMI 2.0 support to DW HDMI QP TX |

Commit Message

Cristian Ciocaltea Sept. 1, 2026, 6:50 p.m. UTC 
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 <mripard@kernel.org>
Tested-by: Maud Spierings <maud_spierings@hotmail.com>
Tested-by: Diederik de Haas <diederik@cknow-tech.com>  # NanoPC-T6 LTS, Rock 5B
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
---
 drivers/gpu/drm/display/drm_hdmi_helper.c | 7 +++++++
 1 file changed, 7 insertions(+)
diff mbox series

Patch

diff --git a/drivers/gpu/drm/display/drm_hdmi_helper.c b/drivers/gpu/drm/display/drm_hdmi_helper.c
index bf1c7963b984..f85cce3d6254 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) {