[PATCH 1/5][SRU][OEM-5.14/Jammy] drm/amd/display: Fix for link encoder access for MST.

[You-Sheng Yang]

From: Meenakshikumar Somasundaram <meenakshikumar.somasundaram at amd.com>

BugLink: https://bugs.launchpad.net/bugs/1991974

[Why]
Link encoder in the link could be null for certain links.

[How]
If link encoder in the link is null then get the link encoder
from the stream.

Reviewed-by: Jun Lei <Jun.Lei at amd.com>
Acked-by: Anson Jacob <Anson.Jacob at amd.com>
Signed-off-by: Meenakshikumar Somasundaram <meenakshikumar.somasundaram at amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
(cherry picked from commit e3ab29aa8c680f31ad1a53a0a1b3a54367dd473d)
Signed-off-by: You-Sheng Yang (vicamo) <vicamo.yang at canonical.com>
---
 drivers/gpu/drm/amd/display/dc/core/dc_link.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
index 7ce379d01612..c4860c2c73fd 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -3111,7 +3111,7 @@ enum dc_status dc_link_allocate_mst_payload(struct pipe_ctx *pipe_ctx)
 {
 	struct dc_stream_state *stream = pipe_ctx->stream;
 	struct dc_link *link = stream->link;
-	struct link_encoder *link_encoder = link->link_enc;
+	struct link_encoder *link_encoder = NULL;
 	struct stream_encoder *stream_encoder = pipe_ctx->stream_res.stream_enc;
 	struct dp_mst_stream_allocation_table proposed_table = {0};
 	struct fixed31_32 avg_time_slots_per_mtp;
@@ -3121,6 +3121,13 @@ enum dc_status dc_link_allocate_mst_payload(struct pipe_ctx *pipe_ctx)
 	enum act_return_status ret;
 	DC_LOGGER_INIT(link->ctx->logger);
 
+	/* Link encoder may have been dynamically assigned to non-physical display endpoint. */
+	if (link->ep_type == DISPLAY_ENDPOINT_PHY)
+		link_encoder = link->link_enc;
+	else if (link->dc->res_pool->funcs->link_encs_assign)
+		link_encoder = link_enc_cfg_get_link_enc_used_by_stream(pipe_ctx->stream->ctx->dc, stream);
+	ASSERT(link_encoder);
+
 	/* enable_link_dp_mst already check link->enabled_stream_count
 	 * and stream is in link->stream[]. This is called during set mode,
 	 * stream_enc is available.
@@ -3212,7 +3219,7 @@ static enum dc_status deallocate_mst_payload(struct pipe_ctx *pipe_ctx)
 {
 	struct dc_stream_state *stream = pipe_ctx->stream;
 	struct dc_link *link = stream->link;
-	struct link_encoder *link_encoder = link->link_enc;
+	struct link_encoder *link_encoder = NULL;
 	struct stream_encoder *stream_encoder = pipe_ctx->stream_res.stream_enc;
 	struct dp_mst_stream_allocation_table proposed_table = {0};
 	struct fixed31_32 avg_time_slots_per_mtp = dc_fixpt_from_int(0);
@@ -3220,6 +3227,13 @@ static enum dc_status deallocate_mst_payload(struct pipe_ctx *pipe_ctx)
 	bool mst_mode = (link->type == dc_connection_mst_branch);
 	DC_LOGGER_INIT(link->ctx->logger);
 
+	/* Link encoder may have been dynamically assigned to non-physical display endpoint. */
+	if (link->ep_type == DISPLAY_ENDPOINT_PHY)
+		link_encoder = link->link_enc;
+	else if (link->dc->res_pool->funcs->link_encs_assign)
+		link_encoder = link_enc_cfg_get_link_enc_used_by_stream(pipe_ctx->stream->ctx->dc, stream);
+	ASSERT(link_encoder);
+
 	/* deallocate_mst_payload is called before disable link. When mode or
 	 * disable/enable monitor, new stream is created which is not in link
 	 * stream[] yet. For this, payload is not allocated yet, so de-alloc
-- 
2.37.2