From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C7AFBC282C6 for ; Sat, 26 Jan 2019 01:24:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A2C7B218F0 for ; Sat, 26 Jan 2019 01:24:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728398AbfAZBYo (ORCPT ); Fri, 25 Jan 2019 20:24:44 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41934 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725550AbfAZBYn (ORCPT ); Fri, 25 Jan 2019 20:24:43 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DD71819D323; Sat, 26 Jan 2019 01:24:42 +0000 (UTC) Received: from malachite.bss.redhat.com (dhcp-10-20-1-11.bss.redhat.com [10.20.1.11]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6E3911851B; Sat, 26 Jan 2019 01:24:37 +0000 (UTC) From: Lyude Paul To: intel-gfx@lists.freedesktop.org Cc: Todd Previte , Dave Airlie , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , stable@vger.kernel.org, David Airlie , Daniel Vetter , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: [PATCH] drm/i915: Don't send MST hotplugs until after resume Date: Fri, 25 Jan 2019 20:24:35 -0500 Message-Id: <20190126012436.31382-1-lyude@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Sat, 26 Jan 2019 01:24:43 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Turns out we are sending a lot more hotplug events then we need, and this is causing some pretty serious issues. Currently, we call intel_dp_mst_resume() in i915_drm_resume() well before we have any sort of hotplugging setup. This is a pretty big problem, because in practice it will generally result in throwing the power domain refcounts out of wack. For instance: On my T480s, removing a previously connected topology before the system finishes resuming causes drm_kms_helper_hotplug_event() to be called before HPD is setup again, which causes us to do a connector reprobe, which then causes intel_dp_detect() to be called on all DP devices -including- the eDP display. From there, intel_dp_detect() is run on the eDP display which triggers DPCD transactions. Those DPCD transactions then cause us to call edp_panel_vdd_on(), which then causes us to grab an additional wakeref to the relevant power wells (PORT_DDI_A_IO on this machine). >From there, this wakeref is never released which then causes the next suspend/resume cycle to entirely fail due to the hardware not being powered off correctly. This sucks really badly, and I don't see any decent way to actually fix this in intel_dp_detect() easily. Additionally, I don't even think it'd be worth the time now since we're not expecting to handle any kind of connector reprobing at the point in which we call intel_dp_mst_resume(), but we also can't move intel_dp_mst_resume() any higher in the resume process since MST topologies need to be resumed before intel_display_resume() is called. However, there's a light at the end of the tunnel! After reading through a lot of code dozens of times, it occurred to me that we -never- actually need to send hotplug events when calling drm_dp_mst_topology_mgr_set_mst() since we send hotplug events in drm_dp_destroy_connector_work(). Imagine that! So, since we only seem to call intel_dp_mst_check_status() to disable MST on the encoder in question and then send a hotplug, get rid of this and instead just disable MST mode when a hub fails in intel_dp_mst_resume(). From there, drm_dp_destroy_connector_work() will eventually send the hotplug event. Signed-off-by: Lyude Paul Fixes: 0e32b39ceed6 ("drm/i915: add DP 1.2 MST support (v0.7)") Cc: Todd Previte Cc: Dave Airlie Cc: Jani Nikula Cc: Joonas Lahtinen Cc: Rodrigo Vivi Cc: intel-gfx@lists.freedesktop.org Cc: # v3.17+ --- drivers/gpu/drm/i915/intel_dp.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 681e88405ada..c2399acf177b 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -7096,7 +7096,10 @@ void intel_dp_mst_resume(struct drm_i915_private *dev_priv) continue; ret = drm_dp_mst_topology_mgr_resume(&intel_dp->mst_mgr); - if (ret) - intel_dp_check_mst_status(intel_dp); + if (ret) { + intel_dp->is_mst = false; + drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr, + false); + } } } -- 2.20.1