From patchwork Fri Jul 8 15:37:35 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: cpaul@redhat.com X-Patchwork-Id: 9221231 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id B1B9860467 for ; Fri, 8 Jul 2016 15:38:45 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A388A28877 for ; Fri, 8 Jul 2016 15:38:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9805E288BD; Fri, 8 Jul 2016 15:38:45 +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=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8F40828877 for ; Fri, 8 Jul 2016 15:38:44 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 402116E297; Fri, 8 Jul 2016 15:38:42 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8A3C46E297; Fri, 8 Jul 2016 15:38:40 +0000 (UTC) Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D694C3DF; Fri, 8 Jul 2016 15:38:39 +0000 (UTC) Received: from ecstaticemu.bos.redhat.com (dhcp-25-142.bos.redhat.com [10.18.25.142]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u68Fcbox018756; Fri, 8 Jul 2016 11:38:38 -0400 From: Lyude To: amd-gfx@lists.freedesktop.org Subject: [PATCH] drm/amdgpu: Disable RPM helpers while reprobing connectors on resume Date: Fri, 8 Jul 2016 11:37:35 -0400 Message-Id: <1467992256-23832-1-git-send-email-cpaul@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 08 Jul 2016 15:38:40 +0000 (UTC) Cc: Tom St Denis , Jammy Zhou , open list , stable@vger.kernel.org, "open list:RADEON and AMDGPU DRM DRIVERS" , Alex Deucher , Lyude , Flora Cui , =?UTF-8?q?Christian=20K=C3=B6nig?= , Monk Liu X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP Just about all of amdgpu's connector probing functions try to acquire runtime PM refs. If we try to do this in the context of amdgpu_resume_kms by calling drm_helper_hpd_irq_event(), we end up deadlocking the system. Since we're guaranteed to be holding the spinlock for RPM in amdgpu_resume_kms, and we already know the GPU is in working order, we need to prevent the RPM helpers from trying to run during the initial connector reprobe on resume. There's a couple of solutions I've explored for fixing this, but this one by far seems to be the simplest and most reliable (plus I'm pretty sure that's what disable_depth is there for anyway). Reproduction recipe: - Get any laptop dual GPUs using PRIME - Make sure runtime PM is enabled for amdgpu - Boot the machine - If the machine managed to boot without hanging, switch out of X to another VT. This should definitely cause X to hang infinitely. Cc: stable@vger.kernel.org Signed-off-by: Lyude --- drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c index 6e92008..46c1fee 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c @@ -1841,7 +1841,19 @@ int amdgpu_resume_kms(struct drm_device *dev, bool resume, bool fbcon) } drm_kms_helper_poll_enable(dev); + + /* + * Most of the connector probing functions try to acquire runtime pm + * refs to ensure that the GPU is powered on when connector polling is + * performed. Since we're calling this from a runtime PM callback, + * trying to acquire rpm refs will cause us to deadlock. + * + * Since we're guaranteed to be holding the rpm lock, it's safe to + * temporarily disable the rpm helpers so this doesn't deadlock us. + */ + dev->dev->power.disable_depth++; drm_helper_hpd_irq_event(dev); + dev->dev->power.disable_depth--; if (fbcon) { amdgpu_fbdev_set_suspend(adev, 0);