From patchwork Mon Jan 28 20:56:01 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lyude Paul X-Patchwork-Id: 10784765 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BEF3D1390 for ; Mon, 28 Jan 2019 20:56:27 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AD59229F23 for ; Mon, 28 Jan 2019 20:56:27 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A20572B639; Mon, 28 Jan 2019 20:56:27 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 292CF29F23 for ; Mon, 28 Jan 2019 20:56:27 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id D2DEF6E547; Mon, 28 Jan 2019 20:56:22 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by gabe.freedesktop.org (Postfix) with ESMTPS id 91DFE6E547; Mon, 28 Jan 2019 20:56:18 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id EF21980F7D; Mon, 28 Jan 2019 20:56:17 +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 A21B55D73F; Mon, 28 Jan 2019 20:56:16 +0000 (UTC) From: Lyude Paul To: intel-gfx@lists.freedesktop.org Date: Mon, 28 Jan 2019 15:56:01 -0500 Message-Id: <20190128205603.16372-2-lyude@redhat.com> In-Reply-To: <20190128205603.16372-1-lyude@redhat.com> References: <20190128205603.16372-1-lyude@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Mon, 28 Jan 2019 20:56:18 +0000 (UTC) Subject: [Intel-gfx] [PATCH v2 1/3] drm/i915: Block fbdev HPD processing during suspend X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Todd Previte , dri-devel@lists.freedesktop.org, David Airlie , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Dave Airlie Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP 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. 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 | 30 +++++++++++++++++++++++++++++- 2 files changed, 39 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h index 85b913ea6e80..c8549588b2ce 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..3a6c0bebaaf9 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 +755,23 @@ 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) +{ + mutex_lock(&ifbdev->hpd_lock); + ifbdev->hpd_suspended = state == FBINFO_STATE_SUSPENDED; + if (ifbdev->hpd_waiting) { + ifbdev->hpd_waiting = false; + + DRM_DEBUG_KMS("Handling delayed fbcon HPD event\n"); + drm_fb_helper_hotplug_event(&ifbdev->helper); + } + mutex_unlock(&ifbdev->hpd_lock); +} + void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool synchronous) { struct drm_i915_private *dev_priv = to_i915(dev); @@ -775,6 +793,7 @@ 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 { /* @@ -802,6 +821,8 @@ 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) @@ -812,8 +833,15 @@ void intel_fbdev_output_poll_changed(struct drm_device *dev) return; intel_fbdev_sync(ifbdev); - if (ifbdev->vma || ifbdev->helper.deferred_setup) + + mutex_lock(&ifbdev->hpd_lock); + if (ifbdev->hpd_suspended) { + DRM_DEBUG_KMS("fbdev HPD event deferred until resume\n"); + ifbdev->hpd_waiting = true; + } else if (ifbdev->vma || ifbdev->helper.deferred_setup) { drm_fb_helper_hotplug_event(&ifbdev->helper); + } + mutex_unlock(&ifbdev->hpd_lock); } void intel_fbdev_restore_mode(struct drm_device *dev)