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 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 83172CA5FAD for ; Tue, 29 Sep 2026 19:01:56 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E743910F006; Tue, 29 Sep 2026 19:01:55 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="RAipOS4H"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.18]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6463610F03F for ; Tue, 29 Sep 2026 19:01:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1790708514; x=1822244514; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=0+/tvSi1MDXNSAgNR6fmMhG5nOLszHkdDS8hIQKWrsc=; b=RAipOS4HVV/TNE4CjrE2pc7Myzn6HLgZ3MhkuC10ODsjGI4rPnd+ZRme sKbgIAqPXRXWwghC6oMGLhdAiq2kmY9bQGvxkKNryexqHeMrL3z9Yae3/ wIf7YwlvVJ/xWxa2Oksd3ajjPLSJ55+U5TH+oLNZQWNewidvtZurbb+Ho HgiAXf54CT56clSGwE4G+e6VPD88nfNONNydXuV9hYvJkmUZzkYHjbEtY BBcrT7yCz80Zb0vYLXk5Rw+8HijEL83WYfa/lTybMcBXDmkCUtr8INc2U dqUQJp0aSy7RqmlKNjJnyRiG8MNwd6r8eO7gYnQXE9FEphtURYM9RUy0Y w==; X-CSE-ConnectionGUID: pgbCilhYQfizUpIxEYEamA== X-CSE-MsgGUID: +hSbkuHgT/ih9ottryf/KA== X-IronPort-AV: E=McAfee;i="6800,10657,11920"; a="90564110" X-IronPort-AV: E=Sophos;i="6.27,130,1787036400"; d="scan'208";a="90564110" Received: from fmviesa006.fm.intel.com ([10.60.135.146]) by fmvoesa112.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Sep 2026 12:01:53 -0700 X-CSE-ConnectionGUID: D1kEWnMySTSiVntVLPf18g== X-CSE-MsgGUID: 3an4xjkJRfmnBcAKaN8Xmw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,130,1787036400"; d="scan'208";a="274062216" Received: from orsosgc001.jf.intel.com ([10.54.56.63]) by fmviesa006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Sep 2026 12:01:53 -0700 From: Umesh Nerlige Ramappa To: intel-gfx@lists.freedesktop.org, vinay.belgaumkar@intel.com Cc: dev@lankhorst.se Subject: [PATCH 1/3] drm/i915/pmu: Disable on PREEMPT_RT Date: Tue, 29 Sep 2026 12:01:49 -0700 Message-ID: <20260929190147.2886670-6-umesh.nerlige.ramappa@intel.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260929190147.2886670-5-umesh.nerlige.ramappa@intel.com> References: <20260929190147.2886670-5-umesh.nerlige.ramappa@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" From: Maarten Lankhorst I tried to come up with alternative and lockless approaches to make pmu work, but since the perf events are run in atomic context on PREEMPT_RT, ordinary spinlocks no longer work and forcewake and register accesses become problematic. Disable perf events on PREEMPT_RT for now, without affecting !PREEMPT_RT users. Signed-off-by: Maarten Lankhorst --- v2: s/reeturn/return/ --- drivers/gpu/drm/i915/i915_pmu.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c index 1c3bafda9c70..9ea5626399e5 100644 --- a/drivers/gpu/drm/i915/i915_pmu.c +++ b/drivers/gpu/drm/i915/i915_pmu.c @@ -1156,6 +1156,16 @@ void i915_pmu_register(struct drm_i915_private *i915) }; int ret = -ENOMEM; + /* + * PREEMPT_RT has problems with forcewake. Forcewake is used by the + * engine 'busy' event when guc submission is enabled, and to measure + * rc6 residency. + * + * Disable pmu events on PREEMPT_RT entirely to prevent deadlocks. + */ + if (IS_ENABLED(CONFIG_PREEMPT_RT)) + return; + spin_lock_init(&pmu->lock); hrtimer_setup(&pmu->timer, i915_sample, CLOCK_MONOTONIC, HRTIMER_MODE_REL); init_rc6(pmu); -- 2.55.0