From patchwork Wed Apr 20 15:56:20 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "David E. Box" X-Patchwork-Id: 12820545 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20EDEC433F5 for ; Wed, 20 Apr 2022 16:08:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1380349AbiDTQLD (ORCPT ); Wed, 20 Apr 2022 12:11:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355118AbiDTQLD (ORCPT ); Wed, 20 Apr 2022 12:11:03 -0400 Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3579731227; Wed, 20 Apr 2022 09:08:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1650470897; x=1682006897; h=from:to:subject:date:message-id:in-reply-to:references: mime-version:content-transfer-encoding; bh=vJzQon2YEQAxP+wKoJedMbeahF5JTPiVjBzVDAVVuhg=; b=dzLOZubnysi2dhLrFX/FSrUYFceEtrvjsjBbBJes4B6IvlcvWbJetxXh fN/1AZqeKAJusVcNVgQWiP1v5vO2iiL78SneNyeYRysUMLVz9v+QRYCCi HQ6cpn1x5ZC4hbvnUIf8apuLjrCaeo4AE3/A3e/glEr6+A5WfgrjV344M XnFfep94ij4zOWa9bRgbIplYkq7SuwRnZvek6+apzwe5Yi03lHFnqarFm ivWf+qpNMzywBwK/OtMg5fS5k6DWAFuUZrHnie5rto8LZU3a0dXe8/jr/ 7//r8YRE2inqpWZTvrkBC8GzG/cC7UtUKR3wIC8qV8ASvHdKjgMxK/Kl2 w==; X-IronPort-AV: E=McAfee;i="6400,9594,10323"; a="244004001" X-IronPort-AV: E=Sophos;i="5.90,276,1643702400"; d="scan'208";a="244004001" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Apr 2022 08:56:23 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.90,276,1643702400"; d="scan'208";a="702687380" Received: from linux.intel.com ([10.54.29.200]) by fmsmga001.fm.intel.com with ESMTP; 20 Apr 2022 08:56:23 -0700 Received: from debox1-desk4.lan (unknown [10.212.213.71]) by linux.intel.com (Postfix) with ESMTP id E33F6580812; Wed, 20 Apr 2022 08:56:22 -0700 (PDT) From: "David E. Box" To: hdegoede@redhat.com, david.e.box@linux.intel.com, markgross@kernel.org, platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/3] platform/x86/intel/sdsi: Handle leaky bucket Date: Wed, 20 Apr 2022 08:56:20 -0700 Message-Id: <20220420155622.1763633-2-david.e.box@linux.intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220420155622.1763633-1-david.e.box@linux.intel.com> References: <20220420155622.1763633-1-david.e.box@linux.intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: platform-driver-x86@vger.kernel.org To prevent an agent from indefinitely holding the mailbox firmware has implemented a leaky bucket algorithm. Repeated access to the mailbox may now incur a delay of up to 2.1 seconds. Add a retry loop that tries for up to 2.5 seconds to acquire the mailbox. Fixes: 2546c6000430 ("platform/x86: Add Intel Software Defined Silicon driver") Signed-off-by: David E. Box --- drivers/platform/x86/intel/sdsi.c | 32 ++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-) diff --git a/drivers/platform/x86/intel/sdsi.c b/drivers/platform/x86/intel/sdsi.c index 11d14cc0ff0a..11f211402479 100644 --- a/drivers/platform/x86/intel/sdsi.c +++ b/drivers/platform/x86/intel/sdsi.c @@ -51,6 +51,8 @@ #define MBOX_TIMEOUT_US 2000 #define MBOX_TIMEOUT_ACQUIRE_US 1000 #define MBOX_POLLING_PERIOD_US 100 +#define MBOX_ACQUIRE_NUM_RETRIES 5 +#define MBOX_ACQUIRE_RETRY_DELAY_MS 500 #define MBOX_MAX_PACKETS 4 #define MBOX_OWNER_NONE 0x00 @@ -263,7 +265,7 @@ static int sdsi_mbox_acquire(struct sdsi_priv *priv, struct sdsi_mbox_info *info { u64 control; u32 owner; - int ret; + int ret, retries = 0; lockdep_assert_held(&priv->mb_lock); @@ -273,13 +275,29 @@ static int sdsi_mbox_acquire(struct sdsi_priv *priv, struct sdsi_mbox_info *info if (owner != MBOX_OWNER_NONE) return -EBUSY; - /* Write first qword of payload */ - writeq(info->payload[0], priv->mbox_addr); + /* + * If there has been no recent transaction and no one owns the mailbox, + * we should acquire it in under 1ms. However, if we've accessed it + * recently it may take up to 2.1 seconds to acquire it again. + */ + do { + /* Write first qword of payload */ + writeq(info->payload[0], priv->mbox_addr); + + /* Check for ownership */ + ret = readq_poll_timeout(priv->control_addr, control, + FIELD_GET(CTRL_OWNER, control) == MBOX_OWNER_INBAND, + MBOX_POLLING_PERIOD_US, MBOX_TIMEOUT_ACQUIRE_US); + + if (FIELD_GET(CTRL_OWNER, control) == MBOX_OWNER_NONE && + retries++ < MBOX_ACQUIRE_NUM_RETRIES) { + msleep(MBOX_ACQUIRE_RETRY_DELAY_MS); + continue; + } - /* Check for ownership */ - ret = readq_poll_timeout(priv->control_addr, control, - FIELD_GET(CTRL_OWNER, control) & MBOX_OWNER_INBAND, - MBOX_POLLING_PERIOD_US, MBOX_TIMEOUT_ACQUIRE_US); + /* Either we got it or someone else did. */ + break; + } while (true); return ret; }