From mboxrd@z Thu Jan 1 00:00:00 1970 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 991ADC433F5 for ; Mon, 29 Nov 2021 21:54:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232433AbhK2V6B (ORCPT ); Mon, 29 Nov 2021 16:58:01 -0500 Received: from mga18.intel.com ([134.134.136.126]:47142 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232552AbhK2V4A (ORCPT ); Mon, 29 Nov 2021 16:56:00 -0500 X-IronPort-AV: E=McAfee;i="6200,9189,10183"; a="222968504" X-IronPort-AV: E=Sophos;i="5.87,273,1631602800"; d="scan'208";a="222968504" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Nov 2021 13:47:25 -0800 X-IronPort-AV: E=Sophos;i="5.87,273,1631602800"; d="scan'208";a="458596091" Received: from ajsteine-mobl13.amr.corp.intel.com (HELO bad-guy.kumite) ([10.252.141.244]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Nov 2021 13:47:25 -0800 From: Ben Widawsky To: linux-cxl@vger.kernel.org Cc: Ben Widawsky , Alison Schofield , Dan Williams , Ira Weiny , Jonathan Cameron , Vishal Verma Subject: [PATCH 4/9] cxl/pci: Implement Interface Ready Timeout Date: Mon, 29 Nov 2021 13:47:16 -0800 Message-Id: <20211129214721.1668325-5-ben.widawsky@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20211129214721.1668325-1-ben.widawsky@intel.com> References: <20211129214721.1668325-1-ben.widawsky@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-cxl@vger.kernel.org The original driver implementation used the doorbell timeout for the Mailbox Interface Ready bit to piggy back off of, since the latter doesn't have a defined timeout. This functionality, introduced in commit 8adaf747c9f0 ("cxl/mem: Find device capabilities"), can now be improved since a timeout has been defined with an ECN to the 2.0 spec. While devices implemented prior to the ECN could have an arbitrarily long wait and still be within spec, the max ECN value (256s) is chosen as the default for all devices. All vendors in the consortium agreed to this amount and so it is reasonable to assume no devices made will exceed this amount. Signed-off-by: Ben Widawsky --- Changes since v1: - Use 60 seconds for timeout instead of 256 (Dan) --- drivers/cxl/pci.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c index 6c8d09fb3a17..b28c220d48ea 100644 --- a/drivers/cxl/pci.c +++ b/drivers/cxl/pci.c @@ -2,6 +2,7 @@ /* Copyright(c) 2020 Intel Corporation. All rights reserved. */ #include #include +#include #include #include #include @@ -298,6 +299,38 @@ static int cxl_pci_mbox_send(struct cxl_dev_state *cxlds, struct cxl_mbox_cmd *c static int cxl_pci_setup_mailbox(struct cxl_dev_state *cxlds) { const int cap = readl(cxlds->regs.mbox + CXLDEV_MBOX_CAPS_OFFSET); + unsigned long timeout; + u64 md_status; + int rc; + + /* + * CXL 2.0 ECN "Add Mailbox Ready Time" defines a capability field to + * dictate how long to wait for the mailbox to become ready. The new + * field allows the device to tell software the amount of time to wait + * before mailbox ready. This field allows for up to 255 seconds. 255 + * seconds is unreasonable long, and longer than other default timeouts + * in the OS. Use the more sane, 60 seconds instead. + * + * 100ms is chosen as the specified pause as it is the value used in the + * CXL Type 3 Memory Device Software Guide. + */ + timeout = jiffies + 60 * HZ; + + rc = check_device_status(cxlds); + if (rc) + return rc; + + do { + md_status = readq(cxlds->regs.memdev + CXLMDEV_STATUS_OFFSET); + if (md_status & CXLMDEV_MBOX_IF_READY) + break; + if (msleep_interruptible(100)) + break; + } while (!time_after(jiffies, timeout)); + + /* It's assumed that once the interface is ready, it will remain ready. */ + if (!(md_status & CXLMDEV_MBOX_IF_READY)) + return -EIO; cxlds->mbox_send = cxl_pci_mbox_send; cxlds->payload_size = -- 2.34.1