From patchwork Thu Sep 14 10:51:23 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: 9952809 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 14518602C9 for ; Thu, 14 Sep 2017 10:52:41 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1093728E92 for ; Thu, 14 Sep 2017 10:52:41 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 015D328EBB; Thu, 14 Sep 2017 10:52:40 +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 5E9C428E92 for ; Thu, 14 Sep 2017 10:52:40 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id D58ED6E151; Thu, 14 Sep 2017 10:52:29 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by gabe.freedesktop.org (Postfix) with ESMTPS id D6C7C6E151 for ; Thu, 14 Sep 2017 10:52:28 +0000 (UTC) Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 14 Sep 2017 03:52:28 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.42,392,1500966000"; d="scan'208";a="151243451" Received: from irsmsx102.ger.corp.intel.com ([163.33.3.155]) by fmsmga005.fm.intel.com with ESMTP; 14 Sep 2017 03:52:27 -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, 14 Sep 2017 11:52:26 +0100 From: =?UTF-8?q?Micha=C5=82=20Winiarski?= To: Date: Thu, 14 Sep 2017 12:51:23 +0200 Message-ID: <20170914105125.3031-1-michal.winiarski@intel.com> X-Mailer: git-send-email 2.13.5 In-Reply-To: <20170914083216.10192-3-michal.winiarski@intel.com> References: <20170914083216.10192-3-michal.winiarski@intel.com> MIME-Version: 1.0 X-Originating-IP: [172.28.171.152] Subject: [Intel-gfx] [PATCH v4 3/5] drm/i915/guc: Simplify GuC doorbell logic 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 All we're really doing is incrementing a simple counter in a doorbell_info struct. We can do without extra variables and a separate counter kept in guc_client. Since it's gone, we're also removing its debugfs. The only functional change here, is that we're no longer treating 0 as a special value. GuC doesn't seem to care, why should we? v2: Restore desc->tail update. v3: Drop the retry loop, assert that doorbell cookie doesn't change behind our back. v4: WARN rather than BUG, use xchg. (Chris) Cc: Chris Wilson Cc: Daniele Ceraolo Spurio Cc: Michal Wajdeczko Cc: Oscar Mateo Suggested-by: Chris Wilson Signed-off-by: Michał Winiarski --- drivers/gpu/drm/i915/i915_debugfs.c | 4 +- drivers/gpu/drm/i915/i915_guc_submission.c | 60 +++++++----------------------- drivers/gpu/drm/i915/intel_uc.h | 1 - 3 files changed, 15 insertions(+), 50 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c index a4c2d0718a70..46ac6091772e 100644 --- a/drivers/gpu/drm/i915/i915_debugfs.c +++ b/drivers/gpu/drm/i915/i915_debugfs.c @@ -2445,8 +2445,8 @@ static void i915_guc_client_info(struct seq_file *m, seq_printf(m, "\tPriority %d, GuC stage index: %u, PD offset 0x%x\n", client->priority, client->stage_id, client->proc_desc_offset); - seq_printf(m, "\tDoorbell id %d, offset: 0x%lx, cookie 0x%x\n", - client->doorbell_id, client->doorbell_offset, client->doorbell_cookie); + seq_printf(m, "\tDoorbell id %d, offset: 0x%lx\n", + client->doorbell_id, client->doorbell_offset); seq_printf(m, "\tWQ size %d, offset: 0x%x, tail %d\n", client->wq_size, client->wq_offset, client->wq_tail); diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c index 84beedae3708..16ce570a0b74 100644 --- a/drivers/gpu/drm/i915/i915_guc_submission.c +++ b/drivers/gpu/drm/i915/i915_guc_submission.c @@ -192,13 +192,12 @@ static int __create_doorbell(struct i915_guc_client *client) doorbell = __get_doorbell(client); doorbell->db_status = GUC_DOORBELL_ENABLED; - doorbell->cookie = client->doorbell_cookie; + doorbell->cookie = 0; err = __guc_allocate_doorbell(client->guc, client->stage_id); - if (err) { + if (err) doorbell->db_status = GUC_DOORBELL_DISABLED; - doorbell->cookie = 0; - } + return err; } @@ -466,57 +465,24 @@ static void guc_reset_wq(struct i915_guc_client *client) client->wq_tail = 0; } -static int guc_ring_doorbell(struct i915_guc_client *client) +static void guc_ring_doorbell(struct i915_guc_client *client) { struct guc_process_desc *desc = __get_process_desc(client); - union guc_doorbell_qw db_cmp, db_exc, db_ret; - union guc_doorbell_qw *db; - int attempt = 2, ret = -EAGAIN; + struct guc_doorbell_info *db; + u32 cookie; /* Update the tail so it is visible to GuC */ desc->tail = client->wq_tail; - /* current cookie */ - db_cmp.db_status = GUC_DOORBELL_ENABLED; - db_cmp.cookie = client->doorbell_cookie; - - /* cookie to be updated */ - db_exc.db_status = GUC_DOORBELL_ENABLED; - db_exc.cookie = client->doorbell_cookie + 1; - if (db_exc.cookie == 0) - db_exc.cookie = 1; - /* pointer of current doorbell cacheline */ - db = (union guc_doorbell_qw *)__get_doorbell(client); - - while (attempt--) { - /* lets ring the doorbell */ - db_ret.value_qw = atomic64_cmpxchg((atomic64_t *)db, - db_cmp.value_qw, db_exc.value_qw); - - /* if the exchange was successfully executed */ - if (db_ret.value_qw == db_cmp.value_qw) { - /* db was successfully rung */ - client->doorbell_cookie = db_exc.cookie; - ret = 0; - break; - } - - /* XXX: doorbell was lost and need to acquire it again */ - if (db_ret.db_status == GUC_DOORBELL_DISABLED) - break; + db = __get_doorbell(client); - DRM_WARN("Cookie mismatch. Expected %d, found %d\n", - db_cmp.cookie, db_ret.cookie); + /* we're not expecting the doorbell cookie to change behind our back */ + cookie = READ_ONCE(db->cookie); + WARN_ON_ONCE(xchg(&db->cookie, cookie + 1) != cookie); - /* update the cookie to newly read cookie from GuC */ - db_cmp.cookie = db_ret.cookie; - db_exc.cookie = db_ret.cookie + 1; - if (db_exc.cookie == 0) - db_exc.cookie = 1; - } - - return ret; + /* XXX: doorbell was lost and need to acquire it again */ + GEM_BUG_ON(db->db_status != GUC_DOORBELL_ENABLED); } /** @@ -550,7 +516,7 @@ static void i915_guc_submit(struct intel_engine_cs *engine) spin_lock_irqsave(&client->wq_lock, flags); guc_wq_item_append(client, rq); - WARN_ON(guc_ring_doorbell(client)); + guc_ring_doorbell(client); client->submissions[engine_id] += 1; diff --git a/drivers/gpu/drm/i915/intel_uc.h b/drivers/gpu/drm/i915/intel_uc.h index d41051688221..f505dcccd613 100644 --- a/drivers/gpu/drm/i915/intel_uc.h +++ b/drivers/gpu/drm/i915/intel_uc.h @@ -66,7 +66,6 @@ struct i915_guc_client { u16 doorbell_id; unsigned long doorbell_offset; - u32 doorbell_cookie; spinlock_t wq_lock; uint32_t wq_offset;