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 6.19 740/781] drm/amd/display: Only use analog link encoder with analog engine
Date: Tue, 24 Feb 2026 17:24:09 -0800
Message-ID: <20260225012417.878704478@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 f402898bd101af3166bde236b7f6a43d926e17a0 ]

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 link encoder code path.

Fixes: 0fbe321a93ce ("drm/amd/display: Implement DCE analog link 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   | 3 ++-
 drivers/gpu/drm/amd/display/dc/resource/dce60/dce60_resource.c | 3 ++-
 drivers/gpu/drm/amd/display/dc/resource/dce80/dce80_resource.c | 3 ++-
 3 files changed, 6 insertions(+), 3 deletions(-)

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 d40d91ec2035f..a916872db7bd4 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
@@ -638,7 +638,8 @@ static struct link_encoder *dce100_link_encoder_create(
 	if (!enc110)
 		return NULL;
 
-	if (enc_init_data->connector.id == CONNECTOR_ID_VGA) {
+	if (enc_init_data->connector.id == CONNECTOR_ID_VGA &&
+	    enc_init_data->analog_engine != ENGINE_ID_UNKNOWN) {
 		dce110_link_encoder_construct(enc110,
 			enc_init_data,
 			&link_enc_feature,
diff --git a/drivers/gpu/drm/amd/display/dc/resource/dce60/dce60_resource.c b/drivers/gpu/drm/amd/display/dc/resource/dce60/dce60_resource.c
index 068fb1df8d889..90d826237cf00 100644
--- a/drivers/gpu/drm/amd/display/dc/resource/dce60/dce60_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/resource/dce60/dce60_resource.c
@@ -733,7 +733,8 @@ static struct link_encoder *dce60_link_encoder_create(
 	if (!enc110)
 		return NULL;
 
-	if (enc_init_data->connector.id == CONNECTOR_ID_VGA) {
+	if (enc_init_data->connector.id == CONNECTOR_ID_VGA &&
+	    enc_init_data->analog_engine != ENGINE_ID_UNKNOWN) {
 		dce60_link_encoder_construct(enc110,
 			enc_init_data,
 			&link_enc_feature,
diff --git a/drivers/gpu/drm/amd/display/dc/resource/dce80/dce80_resource.c b/drivers/gpu/drm/amd/display/dc/resource/dce80/dce80_resource.c
index 8687104cabb72..cde2c2cba1dd6 100644
--- a/drivers/gpu/drm/amd/display/dc/resource/dce80/dce80_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/resource/dce80/dce80_resource.c
@@ -740,7 +740,8 @@ static struct link_encoder *dce80_link_encoder_create(
 	if (!enc110)
 		return NULL;
 
-	if (enc_init_data->connector.id == CONNECTOR_ID_VGA) {
+	if (enc_init_data->connector.id == CONNECTOR_ID_VGA &&
+	    enc_init_data->analog_engine != ENGINE_ID_UNKNOWN) {
 		dce110_link_encoder_construct(enc110,
 			enc_init_data,
 			&link_enc_feature,
-- 
2.51.0