From patchwork Wed Oct 25 20:00:09 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Micha=C5=82_Winiarski?= X-Patchwork-Id: 10027185 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 5DD1E6032C for ; Wed, 25 Oct 2017 20:00:54 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4DCB428CCD for ; Wed, 25 Oct 2017 20:00:54 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 49A4F28CA7; Wed, 25 Oct 2017 20:00:54 +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 598D828CBF for ; Wed, 25 Oct 2017 20:00:45 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0B1A86E04E; Wed, 25 Oct 2017 20:00:45 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0E8946E04E for ; Wed, 25 Oct 2017 20:00:43 +0000 (UTC) Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Oct 2017 13:00:42 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,433,1503385200"; d="scan'208";a="327703480" Received: from irsmsx102.ger.corp.intel.com ([163.33.3.155]) by fmsmga004.fm.intel.com with ESMTP; 25 Oct 2017 13:00:41 -0700 Received: from localhost (172.28.171.152) by IRSMSX102.ger.corp.intel.com (163.33.3.155) with Microsoft SMTP Server (TLS) id 14.3.319.2; Wed, 25 Oct 2017 21:00:41 +0100 From: =?UTF-8?q?Micha=C5=82=20Winiarski?= To: Date: Wed, 25 Oct 2017 22:00:09 +0200 Message-ID: <20171025200020.16636-2-michal.winiarski@intel.com> X-Mailer: git-send-email 2.13.6 In-Reply-To: <20171025200020.16636-1-michal.winiarski@intel.com> References: <20171025200020.16636-1-michal.winiarski@intel.com> MIME-Version: 1.0 X-Originating-IP: [172.28.171.152] Subject: [Intel-gfx] [PATCH v2 01/12] drm/i915/guc: Do not use 0 for GuC doorbell cookie X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.18 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 Apparently, this value is reserved and may be interpreted as changing doorbell ownership. Even though we're not observing any side effects now, let's skip over it to be consistent with the spec. v2: Apply checkpatch (Sagar) Suggested-by: Sagar Arun Kamble Signed-off-by: Michał Winiarski Cc: Chris Wilson Cc: Sagar Arun Kamble Reviewed-by: Sagar Arun Kamble --- drivers/gpu/drm/i915/i915_guc_submission.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c index 07289a4b5bfa..0b61bf18c3f4 100644 --- a/drivers/gpu/drm/i915/i915_guc_submission.c +++ b/drivers/gpu/drm/i915/i915_guc_submission.c @@ -475,9 +475,12 @@ static void guc_ring_doorbell(struct i915_guc_client *client) /* pointer of current doorbell cacheline */ db = __get_doorbell(client); - /* we're not expecting the doorbell cookie to change behind our back */ + /* + * We're not expecting the doorbell cookie to change behind our back, + * we also need to treat 0 as a reserved value. + */ cookie = READ_ONCE(db->cookie); - WARN_ON_ONCE(xchg(&db->cookie, cookie + 1) != cookie); + WARN_ON_ONCE(xchg(&db->cookie, cookie + 1 ?: cookie + 2) != cookie); /* XXX: doorbell was lost and need to acquire it again */ GEM_BUG_ON(db->db_status != GUC_DOORBELL_ENABLED);