From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	=?UTF-8?q?Timur=20Krist=C3=B3f?= <timur.kristof@gmail.com>,
	Alex Hung <alex.hung@amd.com>,
	Alex Deucher <alexander.deucher@amd.com>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.19 741/781] drm/amd/display: Only use analog stream encoder with analog engine
Date: Tue, 24 Feb 2026 17:24:10 -0800
Message-ID: <20260225012417.903148664@linuxfoundation.org>
In-Reply-To: <20260225012359.695468795@linuxfoundation.org>
References: <20260225012359.695468795@linuxfoundation.org>
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6.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Timur Kristóf <timur.kristof@gmail.com>

[ Upstream commit 17ff034f805e032ed1358624a71381f9d6e29e9e ]

Some GPUs have analog connectors that work with a DP bridge chip
and don't actually have an internal DAC: Those should not use
the analog stream encoders.

Fixes: 5834c33fd3f6 ("drm/amd/display: Add concept of analog encoders (v2)")
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 .../gpu/drm/amd/display/dc/resource/dce100/dce100_resource.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/resource/dce100/dce100_resource.c b/drivers/gpu/drm/amd/display/dc/resource/dce100/dce100_resource.c
index a916872db7bd4..83b9abb64bfcb 100644
--- a/drivers/gpu/drm/amd/display/dc/resource/dce100/dce100_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/resource/dce100/dce100_resource.c
@@ -979,7 +979,10 @@ struct stream_encoder *dce100_find_first_free_match_stream_enc_for_link(
 	struct dc_link *link = stream->link;
 	enum engine_id preferred_engine = link->link_enc->preferred_engine;
 
-	if (dc_is_rgb_signal(stream->signal))
+	/* Prefer analog engine if the link encoder has one.
+	 * Otherwise, it's an external encoder.
+	 */
+	if (dc_is_rgb_signal(stream->signal) && link->link_enc->analog_engine != ENGINE_ID_UNKNOWN)
 		preferred_engine = link->link_enc->analog_engine;
 
 	for (i = 0; i < pool->stream_enc_count; i++) {
-- 
2.51.0