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=ham 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 A01F7C282C7 for ; Tue, 29 Jan 2019 19:10:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 728C62184D for ; Tue, 29 Jan 2019 19:10:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729374AbfA2TKZ (ORCPT ); Tue, 29 Jan 2019 14:10:25 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33998 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727056AbfA2TKX (ORCPT ); Tue, 29 Jan 2019 14:10:23 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 73D94A7FC9; Tue, 29 Jan 2019 19:10:22 +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 11E4F5C57C; Tue, 29 Jan 2019 19:10:20 +0000 (UTC) From: Lyude Paul To: intel-gfx@lists.freedesktop.org Cc: Chris Wilson , Todd Previte , Dave Airlie , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Imre Deak , stable@vger.kernel.org, David Airlie , Daniel Vetter , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 1/3] drm/i915: Block fbdev HPD processing during suspend Date: Tue, 29 Jan 2019 14:09:59 -0500 Message-Id: <20190129191001.442-2-lyude@redhat.com> In-Reply-To: <20190129191001.442-1-lyude@redhat.com> References: <20190129191001.442-1-lyude@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Tue, 29 Jan 2019 19:10:22 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When resuming, we check whether or not any previously connected MST topologies are still present and if so, attempt to resume them. If this fails, we disable said MST topologies and fire off a hotplug event so that userspace knows to reprobe. However, sending a hotplug event involves calling drm_fb_helper_hotplug_event(), which in turn results in fbcon doing a connector reprobe in the caller's thread - something we can't do at the point in which i915 calls drm_dp_mst_topology_mgr_resume() since hotplugging hasn't been fully initialized yet. This currently causes some rather subtle but fatal issues. For example, on my T480s the laptop dock connected to it usually disappears during a suspend cycle, and comes back up a short while after the system has been resumed. This guarantees pretty much every suspend and resume cycle, drm_dp_mst_topology_mgr_set_mst(mgr, false); will be caused and in turn, a connector hotplug will occur. Now it's Rute Goldberg time: when the connector hotplug occurs, i915 reprobes /all/ of the connectors, including eDP. However, eDP probing requires that we power on the panel VDD which in turn, grabs a wakeref to the appropriate power domain on the GPU (on my T480s, this is the PORT_DDI_A_IO domain). This is where things start breaking, since this all happens before intel_power_domains_enable() is called we end up leaking the wakeref that was acquired and never releasing it later. Come next suspend/resume cycle, this causes us to fail to shut down the GPU properly, which causes it not to resume properly and die a horrible complicated death. (as a note: this only happens when there's both an eDP panel and MST topology connected which is removed mid-suspend. One or the other seems to always be OK). We could try to fix the VDD wakeref leak, but this doesn't seem like it's worth it at all since we aren't able to handle hotplug detection while resuming anyway. So, let's go with a more robust solution inspired by nouveau: block fbdev from handling hotplug events until we resume fbdev. This allows us to still send sysfs hotplug events to be handled later by user space while we're resuming, while also preventing us from actually processing any hotplug events we receive until it's safe. This fixes the wakeref leak observed on the T480s and as such, also fixes suspend/resume with MST topologies connected on this machine. Changes since v2: * Don't call drm_fb_helper_hotplug_event() under lock, do it after lock (Chris Wilson) * Don't call drm_fb_helper_hotplug_event() in intel_fbdev_output_poll_changed() under lock (Chris Wilson) * Always set ifbdev->hpd_waiting (Chris Wilson) 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: Imre Deak Cc: intel-gfx@lists.freedesktop.org Cc: # v3.17+ --- drivers/gpu/drm/i915/intel_drv.h | 10 +++++++++ drivers/gpu/drm/i915/intel_fbdev.c | 33 +++++++++++++++++++++++++++++- 2 files changed, 42 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h index 90ba5436370e..9ec3d00fbd19 100644 --- a/drivers/gpu/drm/i915/intel_drv.h +++ b/drivers/gpu/drm/i915/intel_drv.h @@ -213,6 +213,16 @@ struct intel_fbdev { unsigned long vma_flags; async_cookie_t cookie; int preferred_bpp; + + /* Whether or not fbdev hpd processing is temporarily suspended */ + bool hpd_suspended : 1; + /* Set when a hotplug was received while HPD processing was + * suspended + */ + bool hpd_waiting : 1; + + /* Protects hpd_suspended */ + struct mutex hpd_lock; }; struct intel_encoder { diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c index 8cf3efe88f02..376ffe842e26 100644 --- a/drivers/gpu/drm/i915/intel_fbdev.c +++ b/drivers/gpu/drm/i915/intel_fbdev.c @@ -681,6 +681,7 @@ int intel_fbdev_init(struct drm_device *dev) if (ifbdev == NULL) return -ENOMEM; + mutex_init(&ifbdev->hpd_lock); drm_fb_helper_prepare(dev, &ifbdev->helper, &intel_fb_helper_funcs); if (!intel_fbdev_init_bios(dev, ifbdev)) @@ -754,6 +755,26 @@ void intel_fbdev_fini(struct drm_i915_private *dev_priv) intel_fbdev_destroy(ifbdev); } +/* Suspends/resumes fbdev processing of incoming HPD events. When resuming HPD + * processing, fbdev will perform a full connector reprobe if a hotplug event + * was received while HPD was suspended. + */ +static void intel_fbdev_hpd_set_suspend(struct intel_fbdev *ifbdev, int state) +{ + bool send_hpd = false; + + mutex_lock(&ifbdev->hpd_lock); + ifbdev->hpd_suspended = state == FBINFO_STATE_SUSPENDED; + send_hpd = !ifbdev->hpd_suspended && ifbdev->hpd_waiting; + ifbdev->hpd_waiting = false; + mutex_unlock(&ifbdev->hpd_lock); + + if (send_hpd) { + DRM_DEBUG_KMS("Handling delayed fbcon HPD event\n"); + drm_fb_helper_hotplug_event(&ifbdev->helper); + } +} + void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool synchronous) { struct drm_i915_private *dev_priv = to_i915(dev); @@ -775,6 +796,7 @@ void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool synchronous */ if (state != FBINFO_STATE_RUNNING) flush_work(&dev_priv->fbdev_suspend_work); + console_lock(); } else { /* @@ -802,17 +824,26 @@ void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool synchronous drm_fb_helper_set_suspend(&ifbdev->helper, state); console_unlock(); + + intel_fbdev_hpd_set_suspend(ifbdev, state); } void intel_fbdev_output_poll_changed(struct drm_device *dev) { struct intel_fbdev *ifbdev = to_i915(dev)->fbdev; + bool send_hpd; if (!ifbdev) return; intel_fbdev_sync(ifbdev); - if (ifbdev->vma || ifbdev->helper.deferred_setup) + + mutex_lock(&ifbdev->hpd_lock); + send_hpd = !ifbdev->hpd_suspended; + ifbdev->hpd_waiting = true; + mutex_unlock(&ifbdev->hpd_lock); + + if (send_hpd && (ifbdev->vma || ifbdev->helper.deferred_setup)) drm_fb_helper_hotplug_event(&ifbdev->helper); } -- 2.20.1