From patchwork Thu Oct 19 18:36:06 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: 10018139 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 EB7E660224 for ; Thu, 19 Oct 2017 18:36:42 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E266328DED for ; Thu, 19 Oct 2017 18:36:42 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D5C4528DF1; Thu, 19 Oct 2017 18:36:42 +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 8075F28DED for ; Thu, 19 Oct 2017 18:36:42 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id DFCE26EB26; Thu, 19 Oct 2017 18:36:41 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by gabe.freedesktop.org (Postfix) with ESMTPS id E480D6EB26 for ; Thu, 19 Oct 2017 18:36:39 +0000 (UTC) Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Oct 2017 11:36:39 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,402,1503385200"; d="scan'208";a="325280313" Received: from irsmsx102.ger.corp.intel.com ([163.33.3.155]) by fmsmga004.fm.intel.com with ESMTP; 19 Oct 2017 11:36:38 -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; Thu, 19 Oct 2017 19:36:37 +0100 From: =?UTF-8?q?Micha=C5=82=20Winiarski?= To: Date: Thu, 19 Oct 2017 20:36:06 +0200 Message-ID: <20171019183619.6235-2-michal.winiarski@intel.com> X-Mailer: git-send-email 2.13.6 In-Reply-To: <20171019183619.6235-1-michal.winiarski@intel.com> References: <20171019183619.6235-1-michal.winiarski@intel.com> MIME-Version: 1.0 X-Originating-IP: [172.28.171.152] Subject: [Intel-gfx] [PATCH 01/14] 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. 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 | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c index a2e8114b739d..02ca2a412c62 100644 --- a/drivers/gpu/drm/i915/i915_guc_submission.c +++ b/drivers/gpu/drm/i915/i915_guc_submission.c @@ -475,9 +475,10 @@ 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);