Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753219AbcDMUud (ORCPT ); Wed, 13 Apr 2016 16:50:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56143 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753161AbcDMUuc (ORCPT ); Wed, 13 Apr 2016 16:50:32 -0400 From: Lyude To: dri-devel@lists.freedesktop.org Cc: Lyude , David Airlie , linux-kernel@vger.kernel.org (open list) Subject: [PATCH] drm/dp/mst: Restore primary hub guid on resume Date: Wed, 13 Apr 2016 16:50:18 -0400 Message-Id: <1460580618-7421-1-git-send-email-cpaul@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1572 Lines: 45 Some hubs are forgetful, and end up forgetting whatever GUID we set previously after we do a suspend/resume cycle. This can lead to hotplugging breaking (along with probably other things) since the hub will start sending connection notifications with the wrong GUID. As such, we need to check on resume whether or not the GUID the hub is giving us is valid. Signed-off-by: Lyude Signed-off-by: Dave Airlie --- drivers/gpu/drm/drm_dp_mst_topology.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index 27fbd79..d2efd78 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -2121,6 +2121,8 @@ int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr) if (mgr->mst_primary) { int sret; + u8 guid[16]; + sret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd, DP_RECEIVER_CAP_SIZE); if (sret != DP_RECEIVER_CAP_SIZE) { DRM_DEBUG_KMS("dpcd read failed - undocked during suspend?\n"); @@ -2135,6 +2137,16 @@ int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr) ret = -1; goto out_unlock; } + + /* Some hubs forget their guids after they resume */ + sret = drm_dp_dpcd_read(mgr->aux, DP_GUID, guid, 16); + if (sret != 16) { + DRM_DEBUG_KMS("dpcd read failed - undocked during suspend?\n"); + ret = -1; + goto out_unlock; + } + drm_dp_check_mstb_guid(mgr->mst_primary, guid); + ret = 0; } else ret = -1; -- 2.5.5