Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lyude Paul , "Jerry (Fangzhi) Zuo" , Alex Deucher Subject: [PATCH 4.19 15/41] drm/amd/dm: Dont forget to attach MST encoders Date: Thu, 6 Dec 2018 15:38:55 +0100 Message-Id: <20181206142951.034168427@linuxfoundation.org> In-Reply-To: <20181206142949.757402551@linuxfoundation.org> References: <20181206142949.757402551@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lyude Paul commit c9e0ab86b2e03154bb898cd2f851827783224727 upstream. The change fixed huge delay in SST daisy chain and S3 soft hang observed in 4.19 kernel rebase. Regression point in drm: drm/fb-helper: Eliminate the .best_encoder() usage The aux sequence is altered due to the failure in drm_connector_for_each_possible_encoder(). The failure is caused by missing attached encoder in the process of adding MST connector.   drm_dp_send_enum_path_resources() aux transaction is pushed after mode probe, which causes conflict to drm_dp_mst_i2c_xfer(), leading to the transaction timeout. Signed-off-by: Lyude Paul Reviewed-by: Jerry (Fangzhi) Zuo Cc: Stable Signed-off-by: Alex Deucher Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 2 ++ 1 file changed, 2 insertions(+) --- 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 @@ -374,6 +374,8 @@ dm_dp_add_mst_connector(struct drm_dp_ms master->connector_id); aconnector->mst_encoder = dm_dp_create_fake_mst_encoder(master); + drm_connector_attach_encoder(&aconnector->base, + &aconnector->mst_encoder->base); /* * TODO: understand why this one is needed