On 10/15/2026 6:30 AM, Hugo Sales wrote:
Currently, create_stream_for_sink() takes the native timing for a scaled
mode from the preferred mode in connector->modes. After fbdev emulation
probes with size limits below the native resolution, as it does when
video= sets a smaller mode, that mode is no longer in the list
If that probe is the last one before a suspend, for example after an
HDMI hotplug, the resume finds no preferred mode, and the panel is
driven with the scaled mode's timing instead of its own
amdgpu_dm_get_native_mode() copies the preferred mode to the encoder on
every probe, before the size limits apply. Fall back to that copy when
connector->modes has no preferred mode. Limit this to eDP and LVDS,
where amdgpu turns scaling on by itself. On other connectors mode_valid
can also leave the preferred mode out, and then the first valid mode is
the right fallback
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/5983
Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Hugo Sales <[email protected]>
Hi Hugo,
Thanks for the patch and the detailed analysis.
This no longer applies to the current amd-staging-drm-next. It
conflicts with commit 3299935e65c0 ("drm/amd/display: Use separate
iterator for preferred mode lookup"), which landed after the tree you
based this on. That commit removed native_mode_found from
create_stream_for_sink() and now checks preferred_mode directly:
if (!preferred_mode)
preferred_mode = list_first_entry_or_null(...);
Could you rebase the series onto the latest amd-staging-drm-next and
send a v2? The change should be mechanical: test !preferred_mode
instead of !native_mode_found, and drop the native_mode_found = true
assignment. The logic stays the same. Patch 2/2 still applies cleanly.
Also, the dm_test_fs_caps_hdmi_vsdb and dm_test_fs_caps_pcon_whitelist
failures you mentioned in the cover letter were fixed by commit
5ac0b4dd2a1f ("drm/amd/display: Fix FreeSync caps tests after common
EDID VSDB switch"). With the series rebased that way, the whole
amdgpu_dm_connector KUnit suite passes on our side, including your new
tests.
Thanks,
Tom
---
.../display/amdgpu_dm/amdgpu_dm_connector.c | 28 +++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
index 428a5f937..a1dc3e287 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
@@ -257,6 +257,8 @@ STATIC_IFN_KUNIT void update_subconnector_property(struct
amdgpu_dm_connector *a
EXPORT_IF_KUNIT(update_subconnector_property);
STATIC_IFN_KUNIT int amdgpu_dm_connector_get_modes(struct drm_connector
*connector);
+STATIC_IFN_KUNIT struct drm_encoder *amdgpu_dm_connector_to_encoder(
+ struct drm_connector *connector);
STATIC_IFN_KUNIT void amdgpu_dm_fbc_init(struct drm_connector *connector)
{
@@ -1470,6 +1472,7 @@ create_stream_for_sink(struct drm_connector *connector,
struct dc_stream_state *stream = NULL;
struct drm_display_mode mode;
struct drm_display_mode saved_mode;
+ struct drm_display_mode native_mode;
struct drm_display_mode *freesync_mode = NULL;
bool native_mode_found = false;
bool recalculate_timing = false;
@@ -1529,6 +1532,31 @@ create_stream_for_sink(struct drm_connector *connector,
break;
}
}
+
+ /*
+ * After a probe with size limits smaller than the preferred mode,
+ * connector->modes no longer has that mode, and the first mode left
+ * would become the stream timing. fbdev emulation probes with limits
+ * that video= can set below the native size. The encoder has a copy of
+ * the preferred mode from amdgpu_dm_get_native_mode(), made on every
+ * probe before the limits apply, so use that copy. Only do this for eDP
+ * and LVDS panels, which take only their native timing. On other
+ * connectors mode_valid can also reject the preferred mode, and then
+ * the first valid mode is the right one
+ */
+ if (!native_mode_found && aconnector && !aconnector->mst_root &&
aconnector->drm_edid &&
+ (connector->connector_type == DRM_MODE_CONNECTOR_eDP ||
+ connector->connector_type == DRM_MODE_CONNECTOR_LVDS)) {
+ struct drm_encoder *encoder =
amdgpu_dm_connector_to_encoder(connector);
+
+ if (encoder && to_amdgpu_encoder(encoder)->native_mode.clock) {
+ drm_mode_copy(&native_mode,
&to_amdgpu_encoder(encoder)->native_mode);
+ drm_mode_set_crtcinfo(&native_mode,
CRTC_INTERLACE_HALVE_V);
+ preferred_mode = &native_mode;
+ native_mode_found = true;
+ }
+ }
+
if (!native_mode_found)
preferred_mode = list_first_entry_or_null(
&connector->modes,
--
2.55.0
