drm/i915/mst: change return value of mst_stream_find_vcpi_slots_for_bpp()

The callers of mst_stream_find_vcpi_slots_for_bpp() don't need the
returned slots for anything. On the contrary, they need to jump through
hoops to just distinguish between success and failure. Just return 0
instead of slots from mst_stream_find_vcpi_slots_for_bpp() for success,
and simplify the callers.

There's a pointless ret local variable that we can drop in the process.

Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/7b3671a548c893b1bb62151d41f90bb8ce842ccc.1735912293.git.jani.nikula@intel.com

Author: jnikula

drivers/gpu/drm/i915/display/intel_dp_mst.c

@@ -226,7 +226,6 @@ static int mst_stream_find_vcpi_slots_for_bpp(struct intel_dp *intel_dp,
 	int bpp, slots = -EINVAL;
 	int dsc_slice_count = 0;
 	int max_dpt_bpp;
-	int ret = 0;
 
 	mst_state = drm_atomic_get_mst_topology_state(state, &intel_dp->mst_mgr);
 	if (IS_ERR(mst_state))
@@ -340,46 +339,37 @@ static int mst_stream_find_vcpi_slots_for_bpp(struct intel_dp *intel_dp,
 		}
 	}
 
-	/* We failed to find a proper bpp/timeslots, return error */
-	if (ret)
-		slots = ret;
-
 	if (slots < 0) {
 		drm_dbg_kms(display->drm, "failed finding vcpi slots:%d\n",
 			    slots);
-	} else {
-		if (!dsc)
-			crtc_state->pipe_bpp = bpp;
-		else
-			crtc_state->dsc.compressed_bpp_x16 = fxp_q4_from_int(bpp);
-		drm_dbg_kms(display->drm, "Got %d slots for pipe bpp %d dsc %d\n",
-			    slots, bpp, dsc);
+		return slots;
 	}
 
-	return slots;
+	if (!dsc)
+		crtc_state->pipe_bpp = bpp;
+	else
+		crtc_state->dsc.compressed_bpp_x16 = fxp_q4_from_int(bpp);
+
+	drm_dbg_kms(display->drm, "Got %d slots for pipe bpp %d dsc %d\n",
+		    slots, bpp, dsc);
+
+	return 0;
 }
 
 static int mst_stream_compute_link_config(struct intel_dp *intel_dp,
 					  struct intel_crtc_state *crtc_state,
 					  struct drm_connector_state *conn_state,
 					  struct link_config_limits *limits)
 {
-	int slots = -EINVAL;
-
 	/*
 	 * FIXME: allocate the BW according to link_bpp, which in the case of
 	 * YUV420 is only half of the pipe bpp value.
 	 */
-	slots = mst_stream_find_vcpi_slots_for_bpp(intel_dp, crtc_state,
-						   fxp_q4_to_int(limits->link.max_bpp_x16),
-						   fxp_q4_to_int(limits->link.min_bpp_x16),
-						   limits,
-						   conn_state, 2 * 3, false);
-
-	if (slots < 0)
-		return slots;
-
-	return 0;
+	return mst_stream_find_vcpi_slots_for_bpp(intel_dp, crtc_state,
+						  fxp_q4_to_int(limits->link.max_bpp_x16),
+						  fxp_q4_to_int(limits->link.min_bpp_x16),
+						  limits,
+						  conn_state, 2 * 3, false);
 }
 
 static int mst_stream_dsc_compute_link_config(struct intel_dp *intel_dp,
@@ -389,7 +379,6 @@ static int mst_stream_dsc_compute_link_config(struct intel_dp *intel_dp,
 {
 	struct intel_display *display = to_intel_display(intel_dp);
 	struct intel_connector *connector = to_intel_connector(conn_state->connector);
-	int slots = -EINVAL;
 	int i, num_bpc;
 	u8 dsc_bpc[3] = {};
 	int min_bpp, max_bpp, sink_min_bpp, sink_max_bpp;
@@ -437,14 +426,9 @@ static int mst_stream_dsc_compute_link_config(struct intel_dp *intel_dp,
 	min_compressed_bpp = intel_dp_dsc_nearest_valid_bpp(display, min_compressed_bpp,
 							    crtc_state->pipe_bpp);
 
-	slots = mst_stream_find_vcpi_slots_for_bpp(intel_dp, crtc_state, max_compressed_bpp,
-						   min_compressed_bpp, limits,
-						   conn_state, 1, true);
-
-	if (slots < 0)
-		return slots;
-
-	return 0;
+	return mst_stream_find_vcpi_slots_for_bpp(intel_dp, crtc_state, max_compressed_bpp,
+						  min_compressed_bpp, limits,
+						  conn_state, 1, true);
 }
 
 static int mst_stream_update_slots(struct intel_dp *intel_dp,