1 files changed, 72 insertions, 9 deletions

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
index 86b63ce1dbf6..39997d977efb 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
@@ -335,28 +335,91 @@ bool dm_helpers_dp_mst_send_payload_allocation(
 	return true;
 }
 
-void dm_dtn_log_begin(struct dc_context *ctx)
+void dm_dtn_log_begin(struct dc_context *ctx,
+	struct dc_log_buffer_ctx *log_ctx)
 {
-	pr_info("[dtn begin]\n");
+	static const char msg[] = "[dtn begin]\n";
+
+	if (!log_ctx) {
+		pr_info("%s", msg);
+		return;
+	}
+
+	dm_dtn_log_append_v(ctx, log_ctx, "%s", msg);
 }
 
 void dm_dtn_log_append_v(struct dc_context *ctx,
-		const char *msg, ...)
+	struct dc_log_buffer_ctx *log_ctx,
+	const char *msg, ...)
 {
-	struct va_format vaf;
 	va_list args;
+	size_t total;
+	int n;
+
+	if (!log_ctx) {
+		/* No context, redirect to dmesg. */
+		struct va_format vaf;
+
+		vaf.fmt = msg;
+		vaf.va = &args;
+
+		va_start(args, msg);
+		pr_info("%pV", &vaf);
+		va_end(args);
 
+		return;
+	}
+
+	/* Measure the output. */
 	va_start(args, msg);
-	vaf.fmt = msg;
-	vaf.va = &args;
+	n = vsnprintf(NULL, 0, msg, args);
+	va_end(args);
+
+	if (n <= 0)
+		return;
+
+	/* Reallocate the string buffer as needed. */
+	total = log_ctx->pos + n + 1;
 
-	pr_info("%pV", &vaf);
+	if (total > log_ctx->size) {
+		char *buf = (char *)kvcalloc(total, sizeof(char), GFP_KERNEL);
+
+		if (buf) {
+			memcpy(buf, log_ctx->buf, log_ctx->pos);
+			kfree(log_ctx->buf);
+
+			log_ctx->buf = buf;
+			log_ctx->size = total;
+		}
+	}
+
+	if (!log_ctx->buf)
+		return;
+
+	/* Write the formatted string to the log buffer. */
+	va_start(args, msg);
+	n = vscnprintf(
+		log_ctx->buf + log_ctx->pos,
+		log_ctx->size - log_ctx->pos,
+		msg,
+		args);
 	va_end(args);
+
+	if (n > 0)
+		log_ctx->pos += n;
 }
 
-void dm_dtn_log_end(struct dc_context *ctx)
+void dm_dtn_log_end(struct dc_context *ctx,
+	struct dc_log_buffer_ctx *log_ctx)
 {
-	pr_info("[dtn end]\n");
+	static const char msg[] = "[dtn end]\n";
+
+	if (!log_ctx) {
+		pr_info("%s", msg);
+		return;
+	}
+
+	dm_dtn_log_append_v(ctx, log_ctx, "%s", msg);
 }
 
 bool dm_helpers_dp_mst_start_top_mgr(