drm/i915/dp: Skip computing a non-DSC link config if DSC is needed

Computing the non-DSC mode link config is redundant once it's determined
that DSC will be needed, so skip computing it. In a follow-up patch this
simplifies setting the link limits which are dependent on the DSC vs.
non-DSC mode.

While at it sanitize the debug print about the MST DSC fallback path,
making it similar to the SST DSC one.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230921195159.2646027-4-imre.deak@intel.com

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 9a38ea58b78765351ea8906dfa04aa7f48a2b299..8c6ff2fa6365472bbe2370f6612c8d8e53bb0722 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -2247,7 +2247,8 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
        struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
        struct link_config_limits limits;
        bool joiner_needs_dsc = false;
-       int ret;
+       bool dsc_needed;
+       int ret = 0;
 
        intel_dp_compute_config_limits(intel_dp, pipe_config,
                                       respect_downstream_limits, &limits);
@@ -2263,13 +2264,20 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
         */
        joiner_needs_dsc = DISPLAY_VER(i915) < 13 && pipe_config->bigjoiner_pipes;
 
-       /*
-        * Optimize for slow and wide for everything, because there are some
-        * eDP 1.3 and 1.4 panels don't work well with fast and narrow.
-        */
-       ret = intel_dp_compute_link_config_wide(intel_dp, pipe_config, conn_state, &limits);
+       dsc_needed = joiner_needs_dsc || intel_dp->force_dsc_en;
+
+       if (!dsc_needed) {
+               /*
+                * Optimize for slow and wide for everything, because there are some
+                * eDP 1.3 and 1.4 panels don't work well with fast and narrow.
+                */
+               ret = intel_dp_compute_link_config_wide(intel_dp, pipe_config,
+                                                       conn_state, &limits);
+               if (ret)
+                       dsc_needed = true;
+       }
 
-       if (ret || joiner_needs_dsc || intel_dp->force_dsc_en) {
+       if (dsc_needed) {
                drm_dbg_kms(&i915->drm, "Try DSC (fallback=%s, joiner=%s, force=%s)\n",
                            str_yes_no(ret), str_yes_no(joiner_needs_dsc),
                            str_yes_no(intel_dp->force_dsc_en));

diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 137d5e6432fa6ca3f9ca753442bdd0f82bfe5786..076c4346dd2d98232ee04d9e7c3de89b15641736 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -337,7 +337,8 @@ static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
        const struct drm_display_mode *adjusted_mode =
                &pipe_config->hw.adjusted_mode;
        struct link_config_limits limits;
-       int ret;
+       bool dsc_needed;
+       int ret = 0;
 
        if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
                return -EINVAL;
@@ -348,15 +349,25 @@ static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
 
        intel_dp_mst_compute_config_limits(intel_dp, pipe_config, &limits);
 
-       ret = intel_dp_mst_compute_link_config(encoder, pipe_config,
-                                              conn_state, &limits);
+       dsc_needed = intel_dp->force_dsc_en;
 
-       if (ret == -EDEADLK)
-               return ret;
+       if (!dsc_needed) {
+               ret = intel_dp_mst_compute_link_config(encoder, pipe_config,
+                                                      conn_state, &limits);
+
+               if (ret == -EDEADLK)
+                       return ret;
+
+               if (ret)
+                       dsc_needed = true;
+       }
 
        /* enable compression if the mode doesn't fit available BW */
-       drm_dbg_kms(&dev_priv->drm, "Force DSC en = %d\n", intel_dp->force_dsc_en);
-       if (ret || intel_dp->force_dsc_en) {
+       if (dsc_needed) {
+               drm_dbg_kms(&dev_priv->drm, "Try DSC (fallback=%s, force=%s)\n",
+                           str_yes_no(ret),
+                           str_yes_no(intel_dp->force_dsc_en));
+
                /*
                 * FIXME: As bpc is hardcoded to 8, as mentioned above,
                 * WARN and ignore the debug flag force_dsc_bpc for now.