From patchwork Wed Mar 21 19:51:38 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 10300263 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 3E27060386 for ; Wed, 21 Mar 2018 19:52:08 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3A706298FE for ; Wed, 21 Mar 2018 19:52:08 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 39002298F7; Wed, 21 Mar 2018 19:52:08 +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]) (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 45E49298F7 for ; Wed, 21 Mar 2018 19:51:57 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 518466E119; Wed, 21 Mar 2018 19:51:56 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7C4446E0EB for ; Wed, 21 Mar 2018 19:51:54 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from haswell.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 11112093-1500050 for multiple; Wed, 21 Mar 2018 19:51:40 +0000 Received: by haswell.alporthouse.com (sSMTP sendmail emulation); Wed, 21 Mar 2018 19:51:39 +0000 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Wed, 21 Mar 2018 19:51:38 +0000 Message-Id: <20180321195139.24774-1-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.16.2 MIME-Version: 1.0 X-Originating-IP: 78.156.65.138 X-Country: code=GB country="United Kingdom" ip=78.156.65.138 Subject: [Intel-gfx] [PATCH 1/2] drm/i915: Use full serialisation around engine->irq_posted 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: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP Using engine->irq_posted for execlists, we are not always serialised by the tasklet as we supposed. On the reset paths, the tasklet is disabled and ignored. Instead, we manipulate the engine->irq_posted directly to account for the reset, but if an interrupt fired before the reset and so wrote to engine->irq_posted, that write may not be flushed from the local CPU's cacheline until much later as the tasklet is already active and so does not generate a mb(). To correctly serialise the interrupt with reset, we need serialisation on the set_bit() itself. And at last Mika can be happy. Signed-off-by: Chris Wilson Cc: Mika Kuoppala Cc: Michał Winiarski CC: Michel Thierry Cc: Jeff McGee Cc: Tvrtko Ursulin --- drivers/gpu/drm/i915/i915_irq.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index fa7310766217..27aee25429b7 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -1405,10 +1405,9 @@ gen8_cs_irq_handler(struct intel_engine_cs *engine, u32 iir) bool tasklet = false; if (iir & GT_CONTEXT_SWITCH_INTERRUPT) { - if (READ_ONCE(engine->execlists.active)) { - __set_bit(ENGINE_IRQ_EXECLIST, &engine->irq_posted); - tasklet = true; - } + if (READ_ONCE(engine->execlists.active)) + tasklet = !test_and_set_bit(ENGINE_IRQ_EXECLIST, + &engine->irq_posted); } if (iir & GT_RENDER_USER_INTERRUPT) {