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From:   "Zuo, Jerry" <Jerry.Zuo@amd.com>
To:     Lyude Paul <lyude@redhat.com>,
        "amd-gfx@lists.freedesktop.org" <amd-gfx@lists.freedesktop.org>
CC:     "Wentland, Harry" <Harry.Wentland@amd.com>,
        "Li, Sun peng (Leo)" <Sunpeng.Li@amd.com>,
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        "Koenig, Christian" <Christian.Koenig@amd.com>,
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        David Airlie <airlied@linux.ie>,
        "Li, Roman" <Roman.Li@amd.com>, "S, Shirish" <Shirish.S@amd.com>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 1/2] drm/amd/dm: Don't forget to attach MST encoders
Thread-Topic: [PATCH 1/2] drm/amd/dm: Don't forget to attach MST encoders
Thread-Index: AQHUfgOWyt5HmDUVPUGZom7lCHrra6VXLz5g
Date:   Mon, 19 Nov 2018 15:00:10 +0000
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References: <20181116232443.1709-1-lyude@redhat.com>
 <20181116232443.1709-2-lyude@redhat.com>
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Reviewed-by: Jerry (Fangzhi) Zuo <Jerry.Zuo@amd.com>

The change fixed MST + SST daisy chain and S3 scenarios. The issue shows hu=
ge delay in MST + SST daisy chain, and soft hang in S3 resume.

The aux sequence is changed by failed iteration search in drm_connector_for=
_each_possible_encoder().=20
The failure of searching for the best encoder for the connector due to the =
miss of attached encoder in the process of adding MST connector.=A0The iter=
ation search takes time to push drm_dp_send_enum_path_resources() aux trans=
action after the mode probe, and causes conflict to drm_dp_mst_i2c_xfer(), =
leading to the aux transaction timeout.

-----Original Message-----
From: Lyude Paul <lyude@redhat.com>=20
Sent: November 16, 2018 6:25 PM
To: amd-gfx@lists.freedesktop.org
Cc: Zuo, Jerry <Jerry.Zuo@amd.com>; Wentland, Harry <Harry.Wentland@amd.com=
>; Li, Sun peng (Leo) <Sunpeng.Li@amd.com>; Deucher, Alexander <Alexander.D=
eucher@amd.com>; Koenig, Christian <Christian.Koenig@amd.com>; Zhou, David(=
ChunMing) <David1.Zhou@amd.com>; David Airlie <airlied@linux.ie>; Li, Roman=
 <Roman.Li@amd.com>; S, Shirish <Shirish.S@amd.com>; Daniel Vetter <daniel.=
vetter@ffwll.ch>; dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel=
.org
Subject: [PATCH 1/2] drm/amd/dm: Don't forget to attach MST encoders

Drive-by fix, this is bound to cause problems somewhere.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: Jerry Zuo <Jerry.Zuo@amd.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/=
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
index d02c32a1039c..0cca1809fdcd 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -342,6 +342,8 @@ dm_dp_add_mst_connector(struct drm_dp_mst_topology_mgr =
*mgr,
 		master->connector_id);
=20
 	aconnector->mst_encoder =3D dm_dp_create_fake_mst_encoder(master);
+	drm_connector_attach_encoder(&aconnector->base,
+				     &aconnector->mst_encoder->base);
=20
 	/*
 	 * TODO: understand why this one is needed
--=20
2.19.1