drm/i915/dp: Restructure the sink/output format selection

Restructure intel_dp_compute_output_format() to resemble the new
intel_hdmi_compute_output_formats().

Again, we basically have two main code paths:
- YCbCr 4:2:0 only modes
- everything else including YCbCr 4:2:0 also modes

Take the exact same approach with the DP code, making the
format selection much less convoluted.

Cc: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20260409101539.22032-5-ville.syrjala@linux.intel.com
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Tested-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index b8b6d62fb275b02724ba8b4bf5b7874e559027ca..ed5841f224ee4697886d456109bd34f51d6c84fa 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -1379,6 +1379,28 @@ intel_dp_mode_valid_downstream(struct intel_connector *connector,
        return MODE_OK;
 }
 
+static enum drm_mode_status
+intel_dp_sink_format_valid(struct intel_connector *connector,
+                          const struct drm_display_mode *mode,
+                          enum intel_output_format sink_format)
+{
+       const struct drm_display_info *info = &connector->base.display_info;
+
+       switch (sink_format) {
+       case INTEL_OUTPUT_FORMAT_YCBCR420:
+               if (!connector->base.ycbcr_420_allowed ||
+                   !drm_mode_is_420(info, mode))
+                       return MODE_NO_420;
+
+               return MODE_OK;
+       case INTEL_OUTPUT_FORMAT_RGB:
+               return MODE_OK;
+       default:
+               MISSING_CASE(sink_format);
+               return MODE_BAD;
+       }
+}
+
 int intel_dp_max_hdisplay_per_pipe(struct intel_display *display)
 {
        return DISPLAY_VER(display) >= 30 ? 6144 : 5120;
@@ -3338,41 +3360,59 @@ static int
 intel_dp_compute_output_format(struct intel_encoder *encoder,
                               struct intel_crtc_state *crtc_state,
                               struct drm_connector_state *conn_state,
-                              bool respect_downstream_limits)
+                              bool respect_downstream_limits,
+                              enum intel_output_format sink_format)
+{
+       struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
+       struct intel_connector *connector = intel_dp->attached_connector;
+       const struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
+
+       if (intel_dp_sink_format_valid(connector, adjusted_mode,
+                                      sink_format) != MODE_OK)
+               return -EINVAL;
+
+       crtc_state->sink_format = sink_format;
+       crtc_state->output_format = intel_dp_output_format(connector, crtc_state->sink_format);
+
+       return intel_dp_compute_link_config(encoder, crtc_state, conn_state,
+                                           respect_downstream_limits);
+}
+
+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)
 {
        struct intel_display *display = to_intel_display(encoder);
        struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
        struct intel_connector *connector = intel_dp->attached_connector;
        const struct drm_display_info *info = &connector->base.display_info;
        const struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
-       bool ycbcr_420_only;
        int ret;
 
-       ycbcr_420_only = drm_mode_is_420_only(info, adjusted_mode);
-
-       if (ycbcr_420_only && !connector->base.ycbcr_420_allowed) {
-               drm_dbg_kms(display->drm,
-                           "YCbCr 4:2:0 mode but YCbCr 4:2:0 output not possible. Falling back to RGB.\n");
-               crtc_state->sink_format = INTEL_OUTPUT_FORMAT_RGB;
-       } else {
-               crtc_state->sink_format = intel_dp_sink_format(connector, adjusted_mode);
-       }
+       if (drm_mode_is_420_only(info, adjusted_mode)) {
+               ret = intel_dp_compute_output_format(encoder, crtc_state, conn_state,
+                                                    respect_downstream_limits,
+                                                    INTEL_OUTPUT_FORMAT_YCBCR420);
 
-       crtc_state->output_format = intel_dp_output_format(connector, crtc_state->sink_format);
+               if (ret) {
+                       drm_dbg_kms(display->drm,
+                                   "YCbCr 4:2:0 mode but YCbCr 4:2:0 output not possible. Falling back to RGB.\n");
 
-       ret = intel_dp_compute_link_config(encoder, crtc_state, conn_state,
-                                          respect_downstream_limits);
-       if (ret) {
-               if (crtc_state->sink_format == INTEL_OUTPUT_FORMAT_YCBCR420 ||
-                   !connector->base.ycbcr_420_allowed ||
-                   !drm_mode_is_420_also(info, adjusted_mode))
-                       return ret;
+                       ret = intel_dp_compute_output_format(encoder, crtc_state, conn_state,
+                                                            respect_downstream_limits,
+                                                            INTEL_OUTPUT_FORMAT_RGB);
+               }
+       } else {
+               ret = intel_dp_compute_output_format(encoder, crtc_state, conn_state,
+                                                    respect_downstream_limits,
+                                                    INTEL_OUTPUT_FORMAT_RGB);
 
-               crtc_state->sink_format = INTEL_OUTPUT_FORMAT_YCBCR420;
-               crtc_state->output_format = intel_dp_output_format(connector,
-                                                                  crtc_state->sink_format);
-               ret = intel_dp_compute_link_config(encoder, crtc_state, conn_state,
-                                                  respect_downstream_limits);
+               if (ret && drm_mode_is_420_also(info, adjusted_mode))
+                       ret = intel_dp_compute_output_format(encoder, crtc_state, conn_state,
+                                                            respect_downstream_limits,
+                                                            INTEL_OUTPUT_FORMAT_YCBCR420);
        }
 
        return ret;
@@ -3547,9 +3587,9 @@ intel_dp_compute_config(struct intel_encoder *encoder,
         * Try to respect downstream TMDS clock limits first, if
         * that fails assume the user might know something we don't.
         */
-       ret = intel_dp_compute_output_format(encoder, pipe_config, conn_state, true);
+       ret = intel_dp_compute_formats(encoder, pipe_config, conn_state, true);
        if (ret)
-               ret = intel_dp_compute_output_format(encoder, pipe_config, conn_state, false);
+               ret = intel_dp_compute_formats(encoder, pipe_config, conn_state, false);
        if (ret)
                return ret;