nc/core_types.h:598 and
  drivers/gpu/drm/amd/display/dc/inc/core_types.h:616.

- Scope and side effects:
  - The change is confined to a single function in one file:
    drivers/gpu/drm/amd/display/dc/link/accessories/link_dp_cts.c, used
    by DP CTS automation and debugfs-triggered training routines (see
    call sites at
    drivers/gpu/drm/amd/display/dc/link/accessories/link_dp_cts.c:591
    and drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c:321,
    :335, :455, :470, :3451, :3466).
  - No architectural changes. No new features. It’s a non-invasive
    correctness fix that avoids iterating over a state that may be
    swapped out mid-loop.
  - Risk of regression is low: logic mirrors existing behavior, only
    replacing “live read from `state->streams`” with a pre-cached
    snapshot. The link-matching predicate is unchanged.

- Impact to users:
  - Prevents kernel crashes during DP LT automation and the debugfs
    paths that adjust preferred link settings/training. While not a
    typical end-user path, it is a valid in-kernel path and a kernel
    crash is a serious bug.

- Alignment with stable rules:
  - Important bugfix that prevents a crash.
  - Small, well-contained, no new features, no architectural
    refactoring.
  - Touches a specific subsystem (AMDGPU DC DP accessory/CTS code) with
    minimal blast radius.
  - No explicit “Cc: stable” tag in the message, but the fix is
    straightforward and clearly justified.

Notes

- The patch still calls
  `dc_update_planes_and_stream(state->clk_mgr->ctx->dc, ...)`. Given the
  state swapping, using `link->dc` instead of `state->clk_mgr->ctx->dc`
  would be even more robust. However, the primary crash cause was
  iterating `state->streams` after the swap; caching streams resolves
  that. The rest of the code’s use of `state` is unchanged from pre-
  patch and has not been reported as problematic in this path.

Conclusion

- This is a clear, minimal crash fix in AMD DC’s DP LT automation path.
  It should be backported to stable trees where the affected code is
  present.

 .../display/dc/link/accessories/link_dp_cts.c  | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/link/accessories/link_dp_cts.c b/drivers/gpu/drm/amd/display/dc/link/accessories/link_dp_cts.c
index b12d61701d4d9..23f41c99fa38c 100644
--- a/drivers/gpu/drm/amd/display/dc/link/accessories/link_dp_cts.c
+++ b/drivers/gpu/drm/amd/display/dc/link/accessories/link_dp_cts.c
@@ -76,6 +76,9 @@ static void dp_retrain_link_dp_test(struct dc_link *link,
 	uint8_t count;
 	int i;
 
+	struct dc_stream_state *streams_on_link[MAX_PIPES];
+	int num_streams_on_link = 0;
+
 	needs_divider_update = (link->dc->link_srv->dp_get_encoding_format(link_setting) !=
 	link->dc->link_srv->dp_get_encoding_format((const struct dc_link_settings *) &link->cur_link_settings));
 
@@ -138,12 +141,19 @@ static void dp_retrain_link_dp_test(struct dc_link *link,
 		pipes[i]->stream_res.tg->funcs->enable_crtc(pipes[i]->stream_res.tg);
 
 	// Set DPMS on with stream update
-	for (i = 0; i < state->stream_count; i++)
-		if (state->streams[i] && state->streams[i]->link && state->streams[i]->link == link) {
-			stream_update.stream = state->streams[i];
+	// Cache all streams on current link since dc_update_planes_and_stream might kill current_state
+	for (i = 0; i < MAX_PIPES; i++) {
+		if (state->streams[i] && state->streams[i]->link && state->streams[i]->link == link)
+			streams_on_link[num_streams_on_link++] = state->streams[i];
+	}
+
+	for (i = 0; i < num_streams_on_link; i++) {
+		if (streams_on_link[i] && streams_on_link[i]->link && streams_on_link[i]->link == link) {
+			stream_update.stream = streams_on_link[i];
 			stream_update.dpms_off = &dpms_off;
-			dc_update_planes_and_stream(state->clk_mgr->ctx->dc, NULL, 0, state->streams[i], &stream_update);
+			dc_update_planes_and_stream(state->clk_mgr->ctx->dc, NULL, 0, streams_on_link[i], &stream_update);
 		}
+	}
 }
 
 static void dp_test_send_link_training(struct dc_link *link)
-- 
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