From: Tony Qi <[email protected]> [WHY] The maximum source viewport width the ASIC can downscale from is held in dc->debug.max_downscale_src_width and is not visible to userspace. Tests (e.g. IGT amd_cursor_overlay scaling subtests) that downscale a plane cannot tell whether a given source width is a genuine hardware limitation or a driver defect, so they cannot correctly distinguish a SKIP from a FAIL.
[HOW] Add a read-only per-connector max_downscale_src_width debugfs file that reports dc->debug.max_downscale_src_width, following the existing internal_display debugfs entry. A value of 0 means no limit. Assisted-by: Claude:opus-4.8 Reviewed-by: Alex Hung <[email protected]> Signed-off-by: Tony Qi <[email protected]> Signed-off-by: Alex Hung <[email protected]> --- .../amd/display/amdgpu_dm/amdgpu_dm_debugfs.c | 20 +++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c index 1a574f508b8d..e4c92b1fa22e 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c @@ -1286,6 +1286,24 @@ static int internal_display_show(struct seq_file *m, void *data) return 0; } +/* + * Returns the maximum source viewport width (in pixels) this ASIC can + * downscale from. A value of 0 means there is no such limit. + * Example usage: cat /sys/kernel/debug/dri/0/eDP-1/max_downscale_src_width + */ +static int max_downscale_src_width_show(struct seq_file *m, void *unused) +{ + struct amdgpu_dm_connector *aconnector = to_amdgpu_dm_connector(m->private); + struct dc_link *link = aconnector->dc_link; + + if (!link) + return -ENODEV; + + seq_printf(m, "%d\n", link->dc->debug.max_downscale_src_width); + + return 0; +} + /* * Returns the number of segments used if ODM Combine mode is enabled. * Example usage: cat /sys/kernel/debug/dri/0/DP-1/odm_combine_segments @@ -3045,6 +3063,7 @@ DEFINE_SHOW_ATTRIBUTE(dmub_tracebuffer); DEFINE_SHOW_ATTRIBUTE(dp_lttpr_status); DEFINE_SHOW_ATTRIBUTE(hdcp_sink_capability); DEFINE_SHOW_ATTRIBUTE(internal_display); +DEFINE_SHOW_ATTRIBUTE(max_downscale_src_width); DEFINE_SHOW_ATTRIBUTE(odm_combine_segments); DEFINE_SHOW_ATTRIBUTE(replay_capability); DEFINE_SHOW_ATTRIBUTE(psr_capability); @@ -3753,6 +3772,7 @@ static const struct { {"force_yuv_pixel_format", &force_yuv_pixel_format_fops}, {"trigger_hotplug", &trigger_hotplug_debugfs_fops}, {"internal_display", &internal_display_fops}, + {"max_downscale_src_width", &max_downscale_src_width_fops}, {"odm_combine_segments", &odm_combine_segments_fops} }; -- 2.43.0
