[PATCH 3/9] drm/i915/hdmi: Restructure 4:2:0 vs. 4:4:4 mode validation

Ville Syrjala
2026-03-30T23:53:59Z

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

Restructure the HDMI mode validation to resemble the new
intel_hdmi_compute_formats(). Keeping the two in sync helps
to avoid different bugs in each.

The main difference between mode_valid() and
intel_hdmi_compute_formats() is that we don't want the
Hail Mary RGB fallback for "4:2:0 only" modes.

Cc: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
drivers/gpu/drm/i915/display/intel_hdmi.c | 60 ++++++++++++-----------
1 file changed, 32 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c b/drivers/gpu/drm/i915/display/intel_hdmi.c
index 16873fc7bcb9..95bd38c620d1 100644
--- a/drivers/gpu/drm/i915/display/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
@@ -2045,6 +2045,27 @@ intel_hdmi_sink_format_valid(struct intel_connector *connector,
}
}

+static enum drm_mode_status
+intel_hdmi_mode_valid_format(struct intel_connector *connector,
+ const struct drm_display_mode *mode,
+ int clock, bool has_hdmi_sink,
+ enum intel_output_format sink_format)
+{
+ struct intel_display *display = to_intel_display(connector);
+ enum drm_mode_status status;
+
+ status = intel_hdmi_sink_format_valid(connector, mode,
+ has_hdmi_sink, sink_format);
+ if (status != MODE_OK)
+ return status;
+
+ status = intel_pfit_mode_valid(display, mode, sink_format, 0);
+ if (status != MODE_OK)
+ return status;
+
+ return intel_hdmi_mode_clock_valid(&connector->base, clock, has_hdmi_sink, sink_format);
+}
+
static enum drm_mode_status
intel_hdmi_mode_valid(struct drm_connector *_connector,
const struct drm_display_mode *mode)
@@ -2052,12 +2073,11 @@ intel_hdmi_mode_valid(struct drm_connector *_connector,
struct intel_connector *connector = to_intel_connector(_connector);
struct intel_display *display = to_intel_display(connector);
struct intel_hdmi *hdmi = intel_attached_hdmi(connector);
+ const struct drm_display_info *info = &connector->base.display_info;
enum drm_mode_status status;
int clock = mode->clock;
int max_dotclk = display->cdclk.max_dotclk_freq;
bool has_hdmi_sink = intel_has_hdmi_sink(hdmi, connector->base.state);
- bool ycbcr_420_only;
- enum intel_output_format sink_format;

status = intel_cpu_transcoder_mode_valid(display, mode);
if (status != MODE_OK)
@@ -2084,36 +2104,20 @@ intel_hdmi_mode_valid(struct drm_connector *_connector,
if (clock > 600000)
return MODE_CLOCK_HIGH;

- ycbcr_420_only = drm_mode_is_420_only(&connector->base.display_info, mode);
+ if (drm_mode_is_420_only(info, mode)) {
+ status = intel_hdmi_mode_valid_format(connector, mode, clock, has_hdmi_sink,
+ INTEL_OUTPUT_FORMAT_YCBCR420);
+ } else {
+ status = intel_hdmi_mode_valid_format(connector, mode, clock, has_hdmi_sink,
+ INTEL_OUTPUT_FORMAT_RGB);

- if (ycbcr_420_only)
- sink_format = INTEL_OUTPUT_FORMAT_YCBCR420;
- else
- sink_format = INTEL_OUTPUT_FORMAT_RGB;
-
- status = intel_pfit_mode_valid(display, mode, sink_format, 0);
+ if (status != MODE_OK && drm_mode_is_420_also(info, mode))
+ status = intel_hdmi_mode_valid_format(connector, mode, clock, has_hdmi_sink,
+ INTEL_OUTPUT_FORMAT_YCBCR420);
+ }
if (status != MODE_OK)
return status;

- status = intel_hdmi_mode_clock_valid(&connector->base, clock, has_hdmi_sink, sink_format);
- if (status != MODE_OK) {
- if (ycbcr_420_only ||
- !connector->base.ycbcr_420_allowed ||
- !drm_mode_is_420_also(&connector->base.display_info, mode))
- return status;
-
- sink_format = INTEL_OUTPUT_FORMAT_YCBCR420;
-
- status = intel_pfit_mode_valid(display, mode, sink_format, 0);
- if (status != MODE_OK)
- return status;
-
- status = intel_hdmi_mode_clock_valid(&connector->base, clock, has_hdmi_sink,
- sink_format);
- if (status != MODE_OK)
- return status;
- }
-
return intel_mode_valid_max_plane_size(display, mode, 1);
}

--
2.52.0