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 E1A82CCA479 for ; Tue, 28 Jun 2022 14:48:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347213AbiF1OsS (ORCPT ); Tue, 28 Jun 2022 10:48:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55404 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347277AbiF1Ore (ORCPT ); Tue, 28 Jun 2022 10:47:34 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 61AD72ED55; Tue, 28 Jun 2022 07:47:32 -0700 (PDT) Received: from fraeml703-chm.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4LXS7D42dFz67tWM; Tue, 28 Jun 2022 22:45:12 +0800 (CST) Received: from lhreml710-chm.china.huawei.com (10.201.108.61) by fraeml703-chm.china.huawei.com (10.206.15.52) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2375.24; Tue, 28 Jun 2022 16:47:29 +0200 Received: from localhost (10.202.226.42) by lhreml710-chm.china.huawei.com (10.201.108.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 28 Jun 2022 15:47:29 +0100 Date: Tue, 28 Jun 2022 15:47:27 +0100 From: Jonathan Cameron To: CC: Dan Williams , Bjorn Helgaas , Lukas Wunner , Alison Schofield , Vishal Verma , "Dave Jiang" , Ben Widawsky , , , Subject: Re: [PATCH V12 6/9] cxl/port: Read CDAT table Message-ID: <20220628154727.0000021c@Huawei.com> In-Reply-To: <20220628041527.742333-7-ira.weiny@intel.com> References: <20220628041527.742333-1-ira.weiny@intel.com> <20220628041527.742333-7-ira.weiny@intel.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.29; i686-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.226.42] X-ClientProxiedBy: lhreml712-chm.china.huawei.com (10.201.108.63) To lhreml710-chm.china.huawei.com (10.201.108.61) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 27 Jun 2022 21:15:24 -0700 ira.weiny@intel.com wrote: > From: Ira Weiny > > The OS will need CDAT data from CXL devices to properly set up > interleave sets. Currently this is supported through a DOE mailbox > which supports CDAT. > > Search the DOE mailboxes available, query CDAT data, and cache the data > for later parsing. > > Provide a sysfs binary attribute to allow dumping of the CDAT. > > Binary dumping is modeled on /sys/firmware/ACPI/tables/ > > The ability to dump this table will be very useful for emulation of real > devices once they become available as QEMU CXL type 3 device emulation will > be able to load this file in. > > This does not support table updates at runtime. It will always provide > whatever was there when first cached. Handling of table updates can be > implemented later. > > Finally create a complete list of CDAT defines within cdat.h for code > wishing to decode the CDAT table. > > Signed-off-by: Jonathan Cameron > Co-developed-by: Jonathan Cameron > Signed-off-by: Ira Weiny One query inline, though I'm fine with it either way, just want to understand your logic in keeping completion when Dan suggested using flush_work() to achieve the same thing. > > --- > Changes from V11: > Adjust for the use of DOE mailbox xarray > Dan Williams: > Remove unnecessary get/put device > Use new BIN_ATTR_ADMIN_RO macro > Flag that CDAT was supported > If there is a read error then the CDAT sysfs > will return a 0 length entry > ... > diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c > index c4c99ff7b55e..4bd479ec0253 100644 > --- a/drivers/cxl/core/pci.c > +++ b/drivers/cxl/core/pci.c > @@ -4,10 +4,12 @@ > +static int cxl_cdat_get_length(struct device *dev, > + struct pci_doe_mb *cdat_mb, > + size_t *length) > +{ > + u32 cdat_request_pl = CDAT_DOE_REQ(0); > + u32 cdat_response_pl[32]; > + DECLARE_COMPLETION_ONSTACK(c); > + struct pci_doe_task task = { > + .prot.vid = PCI_DVSEC_VENDOR_ID_CXL, > + .prot.type = CXL_DOE_PROTOCOL_TABLE_ACCESS, > + .request_pl = &cdat_request_pl, > + .request_pl_sz = sizeof(cdat_request_pl), > + .response_pl = cdat_response_pl, > + .response_pl_sz = sizeof(cdat_response_pl), > + .complete = cxl_doe_task_complete, > + .private = &c, > + }; > + int rc = 0; > + > + rc = pci_doe_submit_task(cdat_mb, &task); > + if (rc < 0) { > + dev_err(dev, "DOE submit failed: %d", rc); > + return rc; > + } > + wait_for_completion(&c); Dan mentioned in his review that we could just use flush_work() and drop the completion logic and callback. Why didn't you go that way? Would want to wrap it up in pci_doe_wait_task() or something like that. > + > + if (task.rv < 1) > + return -EIO; > + > + *length = cdat_response_pl[1]; > + dev_dbg(dev, "CDAT length %zu\n", *length); > + > + return rc; > +} > +