drm/msm/dpu: don't use merge_3d if DSC merge topology is used

DPU supports different topologies for the case when multiple INTFs are
being driven by the single phys_enc. The driver defaults to using 3DMux
in such cases. Don't use it if DSC merge is used instead.
Suggested-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/480922/
Link: https://lore.kernel.org/r/20220406094031.1027376-9-vkoul@kernel.orgSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c

@@ -521,6 +521,22 @@ void dpu_encoder_helper_split_config(
 	}
 }
 
+bool dpu_encoder_use_dsc_merge(struct drm_encoder *drm_enc)
+{
+	struct dpu_encoder_virt *dpu_enc = to_dpu_encoder_virt(drm_enc);
+	int i, intf_count = 0, num_dsc = 0;
+
+	for (i = 0; i < MAX_PHYS_ENCODERS_PER_VIRTUAL; i++)
+		if (dpu_enc->phys_encs[i])
+			intf_count++;
+
+	/* See dpu_encoder_get_topology, we only support 2:2:1 topology */
+	if (dpu_enc->dsc)
+		num_dsc = 2;
+
+	return (num_dsc > 0) && (num_dsc > intf_count);
+}
+
 static struct msm_display_topology dpu_encoder_get_topology(
 			struct dpu_encoder_virt *dpu_enc,
 			struct dpu_kms *dpu_kms,

drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h

@@ -174,4 +174,10 @@ int dpu_encoder_get_vsync_count(struct drm_encoder *drm_enc);
 
 bool dpu_encoder_is_widebus_enabled(const struct drm_encoder *drm_enc);
 
+/**
+ * dpu_encoder_use_dsc_merge - returns true if the encoder uses DSC merge topology.
+ * @drm_enc:    Pointer to previously created drm encoder structure
+ */
+bool dpu_encoder_use_dsc_merge(struct drm_encoder *drm_enc);
+
 #endif /* __DPU_ENCODER_H__ */

drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h

@@ -314,8 +314,10 @@ static inline enum dpu_3d_blend_mode dpu_encoder_helper_get_3d_blend_mode(
 
 	dpu_cstate = to_dpu_crtc_state(phys_enc->parent->crtc->state);
 
+	/* Use merge_3d unless DSC MERGE topology is used */
 	if (phys_enc->split_role == ENC_ROLE_SOLO &&
-	    dpu_cstate->num_mixers == CRTC_DUAL_MIXERS)
+	    dpu_cstate->num_mixers == CRTC_DUAL_MIXERS &&
+	    !dpu_encoder_use_dsc_merge(phys_enc->parent))
 		return BLEND_3D_H_ROW_INT;
 
 	return BLEND_3D_NONE;