On Mon, 31 Mar 2025, Thadeu Lima de Souza Cascardo <casca...@igalia.com> wrote:
> From: Wayne Lin <wayne....@amd.com>
>
> [ Upstream commit bc068194f548ef1f230d96c4398046bf59165992 ]
>
> [Why]
> Observe after suspend/resme, we can't light up mst monitors under specific
> mst hub.
This is already at stable backport stage, but it would really be helpful
to log *which* specific mst hub we're talking about here. Now the
information is lost in time, at least to outsiders.
BR,
Jani.
> The reason is that driver still writes DPCD DP_MSTM_CTRL after LT.
> It's forbidden even we write the same value for that dpcd register.
>
> [How]
> We already resume the mst branch device dpcd settings during
> resume_mst_branch_status(). Leverage drm_dp_mst_topology_queue_probe() to
> only probe the topology, not calling drm_dp_mst_topology_mgr_resume() which
> will set DP_MSTM_CTRL as well.
>
> Reviewed-by: Jerry Zuo <jerry....@amd.com>
> Signed-off-by: Wayne Lin <wayne....@amd.com>
> Signed-off-by: Zaeem Mohamed <zaeem.moha...@amd.com>
> Tested-by: Daniel Wheeler <daniel.whee...@amd.com>
> Signed-off-by: Alex Deucher <alexander.deuc...@amd.com>
> Signed-off-by: Thadeu Lima de Souza Cascardo <casca...@igalia.com>
> ---
> .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 16 ++++------------
> 1 file changed, 4 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index d9a3917d207e..c4c6538eabae 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -3231,8 +3231,7 @@ static int dm_resume(void *handle)
> struct dm_atomic_state *dm_state =
> to_dm_atomic_state(dm->atomic_obj.state);
> enum dc_connection_type new_connection_type = dc_connection_none;
> struct dc_state *dc_state;
> - int i, r, j, ret;
> - bool need_hotplug = false;
> + int i, r, j;
> struct dc_commit_streams_params commit_params = {};
>
> if (dm->dc->caps.ips_support) {
> @@ -3427,23 +3426,16 @@ static int dm_resume(void *handle)
> aconnector->mst_root)
> continue;
>
> - ret = drm_dp_mst_topology_mgr_resume(&aconnector->mst_mgr,
> true);
> -
> - if (ret < 0) {
> - dm_helpers_dp_mst_stop_top_mgr(aconnector->dc_link->ctx,
> - aconnector->dc_link);
> - need_hotplug = true;
> - }
> + drm_dp_mst_topology_queue_probe(&aconnector->mst_mgr);
> }
> drm_connector_list_iter_end(&iter);
>
> - if (need_hotplug)
> - drm_kms_helper_hotplug_event(ddev);
> -
> amdgpu_dm_irq_resume_late(adev);
>
> amdgpu_dm_smu_write_watermarks_table(adev);
>
> + drm_kms_helper_hotplug_event(ddev);
> +
> return 0;
> }
--
Jani Nikula, Intel
