[PATCH v14 14/28] drm/i915/dp: Implement "color format" DRM property

Nicolas Frattaroli
2026-04-23T19:06:24Z

Implement the "color format" DRM property for DP. The values of the
property include RGB, YCbCr420, YCbCr444 and Auto. Auto will pick RGB,
with a fallback to YCbCr420.

The mask of supported formats by the source exposed by the property is
an optimistic scenario, as specific DFP-related caveats can't be
established before an EDID is present.

Should the explicitly requested color format not be supported by the
sink (or by the source in combination with the sink), then an error is
returned to userspace, so that it can make a better choice.

Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
drivers/gpu/drm/i915/display/intel_dp.c | 61 ++++++++++++++++++++++++++++++---
1 file changed, 57 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 299b91d262c3..9334ad9b12e9 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -3414,10 +3414,10 @@ intel_dp_compute_output_format(struct intel_encoder *encoder,
}

static int
-intel_dp_compute_formats(struct intel_encoder *encoder,
- struct intel_crtc_state *crtc_state,
- struct drm_connector_state *conn_state,
- bool respect_downstream_limits)
+intel_dp_compute_formats_auto(struct intel_encoder *encoder,
+ struct intel_crtc_state *crtc_state,
+ struct drm_connector_state *conn_state,
+ bool respect_downstream_limits)
{
struct intel_display *display = to_intel_display(encoder);
struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
@@ -3453,6 +3453,34 @@ intel_dp_compute_formats(struct intel_encoder *encoder,
return ret;
}

+static int
+intel_dp_compute_formats(struct intel_encoder *encoder,
+ struct intel_crtc_state *crtc_state,
+ struct drm_connector_state *conn_state,
+ bool respect_downstream_limits)
+{
+ switch (conn_state->color_format) {
+ case DRM_CONNECTOR_COLOR_FORMAT_RGB444:
+ return intel_dp_compute_output_format(encoder, crtc_state, conn_state,
+ respect_downstream_limits,
+ INTEL_OUTPUT_FORMAT_RGB);
+ case DRM_CONNECTOR_COLOR_FORMAT_YCBCR444:
+ return intel_dp_compute_output_format(encoder, crtc_state, conn_state,
+ respect_downstream_limits,
+ INTEL_OUTPUT_FORMAT_YCBCR444);
+ case DRM_CONNECTOR_COLOR_FORMAT_YCBCR420:
+ return intel_dp_compute_output_format(encoder, crtc_state, conn_state,
+ respect_downstream_limits,
+ INTEL_OUTPUT_FORMAT_YCBCR420);
+ case DRM_CONNECTOR_COLOR_FORMAT_AUTO:
+ return intel_dp_compute_formats_auto(encoder, crtc_state, conn_state,
+ respect_downstream_limits);
+ default:
+ MISSING_CASE(conn_state->color_format);
+ return -EINVAL;
+ }
+}
+
void
intel_dp_audio_compute_config(struct intel_encoder *encoder,
struct intel_crtc_state *pipe_config,
@@ -7009,6 +7037,29 @@ intel_dp_has_gamut_metadata_dip(struct intel_encoder *encoder)
return false;
}

+static void
+intel_dp_attach_color_format_property(struct intel_dp *intel_dp)
+{
+ struct intel_connector *connector = intel_dp->attached_connector;
+ struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+ unsigned long fmts = BIT(DRM_OUTPUT_COLOR_FORMAT_RGB444);
+ bool has_pcon = false;
+
+ if (!connector)
+ return;
+
+ if (dig_port && intel_bios_encoder_is_lspcon(dig_port->base.devdata))
+ has_pcon = true;
+
+ if (has_pcon || source_can_output(intel_dp, INTEL_OUTPUT_FORMAT_YCBCR420))
+ fmts |= BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR420);
+
+ if (has_pcon || source_can_output(intel_dp, INTEL_OUTPUT_FORMAT_YCBCR444))
+ fmts |= BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR444);
+
+ drm_connector_attach_color_format_property(&connector->base, fmts);
+}
+
static void
intel_dp_add_properties(struct intel_dp *intel_dp, struct drm_connector *_connector)
{
@@ -7041,6 +7092,8 @@ intel_dp_add_properties(struct intel_dp *intel_dp, struct drm_connector *_connec

if (HAS_VRR(display))
drm_connector_attach_vrr_capable_property(&connector->base);
+
+ intel_dp_attach_color_format_property(intel_dp);
}

static void

--
2.53.0