drm/amd/display: Add dynamic link encoder selection.

[Why]
Some display endpoints may be programmably mapped to compatible link
encoders. The assignment of link encoders to links has to be dynamic to
accommodate the increased flexibility in comparison to conventional
display endpoints.

[How]
- Add link encoder assignment tracking variables.
- Execute link encoder assignment algorithm before enabling link and
release link encoders from links once they are disabled.

Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

3 files changed, 108 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/display/dc/inc/core_types.h b/drivers/gpu/drm/amd/display/dc/inc/core_types.h
index eb1a19bf0d81..81b92f20d5b6 100644
--- a/drivers/gpu/drm/amd/display/dc/inc/core_types.h
+++ b/drivers/gpu/drm/amd/display/dc/inc/core_types.h
@@ -118,6 +118,27 @@ struct resource_funcs {
 		display_e2e_pipe_params_st *pipes,
 		bool fast_validate);
 
+	/*
+	 * Algorithm for assigning available link encoders to links.
+	 *
+	 * Update link_enc_assignments table and link_enc_avail list accordingly in
+	 * struct resource_context.
+	 */
+	void (*link_encs_assign)(
+			struct dc *dc,
+			struct dc_state *state,
+			struct dc_stream_state *streams[],
+			uint8_t stream_count);
+	/*
+	 * Unassign a link encoder from a stream.
+	 *
+	 * Update link_enc_assignments table and link_enc_avail list accordingly in
+	 * struct resource_context.
+	 */
+	void (*link_enc_unassign)(
+			struct dc_state *state,
+			struct dc_stream_state *stream);
+
 	enum dc_status (*validate_global)(
 		struct dc *dc,
 		struct dc_state *context);
@@ -358,6 +379,12 @@ struct resource_context {
 	uint8_t clock_source_ref_count[MAX_CLOCK_SOURCES];
 	uint8_t dp_clock_source_ref_count;
 	bool is_dsc_acquired[MAX_PIPES];
+	/* A table/array of encoder-to-link assignments. One entry per stream.
+	 * Indexed by stream index in dc_state.
+	 */
+	struct link_enc_assignment link_enc_assignments[MAX_PIPES];
+	/* List of available link encoders. Uses engine ID as encoder identifier. */
+	enum engine_id link_enc_avail[MAX_DIG_LINK_ENCODERS];
 #if defined(CONFIG_DRM_AMD_DC_DCN)
 	bool is_mpc_3dlut_acquired[MAX_PIPES];
 #endif
diff --git a/drivers/gpu/drm/amd/display/dc/inc/hw/link_encoder.h b/drivers/gpu/drm/amd/display/dc/inc/hw/link_encoder.h
index 7f5acd8fb918..80bc99500645 100644
--- a/drivers/gpu/drm/amd/display/dc/inc/hw/link_encoder.h
+++ b/drivers/gpu/drm/amd/display/dc/inc/hw/link_encoder.h
@@ -187,4 +187,17 @@ struct link_encoder_funcs {
 		struct link_encoder *enc);
 };
 
+/*
+ * Used to track assignments of links (display endpoints) to link encoders.
+ *
+ * Entry in link_enc_assignments table in struct resource_context.
+ * Entries only marked valid once encoder assigned to a link and invalidated once unassigned.
+ * Uses engine ID as identifier since PHY ID not relevant for USB4 DPIA endpoint.
+ */
+struct link_enc_assignment {
+	bool valid;
+	struct display_endpoint_id ep_id;
+	enum engine_id eng_id;
+};
+
 #endif /* LINK_ENCODER_H_ */
diff --git a/drivers/gpu/drm/amd/display/dc/inc/link_enc_cfg.h b/drivers/gpu/drm/amd/display/dc/inc/link_enc_cfg.h
new file mode 100644
index 000000000000..ad641632eadd
--- /dev/null
+++ b/drivers/gpu/drm/amd/display/dc/inc/link_enc_cfg.h
@@ -0,0 +1,68 @@
+/*
+ * Copyright 2021 Advanced Micro Devices, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Authors: AMD
+ *
+ */
+
+#ifndef DC_INC_LINK_ENC_CFG_H_
+#define DC_INC_LINK_ENC_CFG_H_
+
+/* This module implements functionality for dynamically assigning DIG link
+ * encoder resources to display endpoints (links).
+ */
+
+#include "core_types.h"
+
+/*
+ * Initialise link encoder resource tracking.
+ */
+void link_enc_cfg_init(
+		struct dc *dc,
+		struct dc_state *state);
+
+/*
+ * Algorithm for assigning available DIG link encoders to streams.
+ *
+ * Update link_enc_assignments table and link_enc_avail list accordingly in
+ * struct resource_context.
+ *
+ * Loop over all streams twice:
+ * a) First assign encoders to unmappable endpoints.
+ * b) Then assign encoders to mappable endpoints.
+ */
+void link_enc_cfg_link_encs_assign(
+		struct dc *dc,
+		struct dc_state *state,
+		struct dc_stream_state *streams[],
+		uint8_t stream_count);
+
+/*
+ * Unassign a link encoder from a stream.
+ *
+ * Update link_enc_assignments table and link_enc_avail list accordingly in
+ * struct resource_context.
+ */
+void link_enc_cfg_link_enc_unassign(
+		struct dc_state *state,
+		struct dc_stream_state *stream);
+
+#endif /* DC_INC_LINK_ENC_CFG_H_ */