[PATCH] drm/amd/display: Reduce Stack Usage in 'dp_retrain_link_dp_test' by heap-allocating 'audio_output'

[Srinivasan Shanmugam]

The function dp_retrain_link_dp_test currently allocates a large
audio_output array on the stack, causing the stack frame size to exceed
the compiler limit (1080 bytes > 1024 bytes).

This change prevents stack overflow issues:
amdgpu/../display/dc/link/accessories/link_dp_cts.c:65:13: warning: stack frame size (1080) exceeds limit (1024) in 'dp_retrain_link_dp_test' [-Wframe-larger-than]
static void dp_retrain_link_dp_test(struct dc_link *link,

This commit refactors the function to dynamically allocate the
audio_output array using kmalloc/kfree, significantly reducing stack
usage.

- Allocates audio_output on the heap instead of stack
- Adds error handling for allocation failure
- Frees allocated memory before function return

Fixes: 9437059b4bfb ("drm/amd/display: Fix Link Override Sequencing When Switching Between DIO/HPO")
Switching Between DIO/HPO")
Cc: Wayne Lin <wayne.lin at amd.com>
Cc: George Shen <george.shen at amd.com>
Cc: Michael Strauss <michael.strauss at amd.com>
Cc: Mike Katsnelson <mike.katsnelson at amd.com>
Cc: Alvin Lee <Alvin.Lee2 at amd.com>
Cc: Ray Wu <ray.wu at amd.com>
Cc: Wenjing Liu <wenjing.liu at amd.com>
Cc: Harry Wentland <harry.wentland at amd.com>
Cc: Tom Chung <chiahsuan.chung at amd.com>
Cc: Roman Li <roman.li at amd.com>
Cc: Alex Hung <alex.hung at amd.com>
Cc: Aurabindo Pillai <aurabindo.pillai at amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam at amd.com>
---
 .../amd/display/dc/link/accessories/link_dp_cts.c   | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

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 2956c2b3ad1a..c4db61cb5079 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
@@ -75,7 +75,16 @@ static void dp_retrain_link_dp_test(struct dc_link *link,
 	bool is_hpo_acquired;
 	uint8_t count;
 	int i;
-	struct audio_output audio_output[MAX_PIPES];
+
+	/* Dynamically allocate audio_output to reduce stack usage */
+	struct audio_output *audio_output;
+
+	audio_output = kmalloc(sizeof(*audio_output) * MAX_PIPES, GFP_KERNEL);
+	if (!audio_output) {
+		/* Allocation failed, handle error gracefully */
+		DC_LOG_ERROR("%s: Failed to allocate audio_output", __func__);
+		return;
+	}
 
 	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));
@@ -144,6 +153,8 @@ static void dp_retrain_link_dp_test(struct dc_link *link,
 			stream_update.dpms_off = &dpms_off;
 			dc_update_planes_and_stream(state->clk_mgr->ctx->dc, NULL, 0, state->streams[i], &stream_update);
 		}
+
+	kfree(audio_output);
 }
 
 static void dp_test_send_link_training(struct dc_link *link)
-- 
2.34.1