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 X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B652EC433EF for ; Fri, 3 Sep 2021 14:35:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 94664610A2 for ; Fri, 3 Sep 2021 14:35:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235393AbhICOgo (ORCPT ); Fri, 3 Sep 2021 10:36:44 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]:3735 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230332AbhICOgo (ORCPT ); Fri, 3 Sep 2021 10:36:44 -0400 Received: from fraeml711-chm.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4H1Kzl024yz67y1k; Fri, 3 Sep 2021 22:33:55 +0800 (CST) Received: from lhreml710-chm.china.huawei.com (10.201.108.61) by fraeml711-chm.china.huawei.com (10.206.15.60) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Fri, 3 Sep 2021 16:35:42 +0200 Received: from localhost (10.52.121.127) by lhreml710-chm.china.huawei.com (10.201.108.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Fri, 3 Sep 2021 15:35:41 +0100 Date: Fri, 3 Sep 2021 15:35:42 +0100 From: Jonathan Cameron To: Ben Widawsky CC: , Alison Schofield , Dan Williams , "Ira Weiny" , Vishal Verma Subject: Re: [PATCH 04/13] cxl: Introduce endpoint decoders Message-ID: <20210903153542.00004518@Huawei.com> In-Reply-To: <20210902195017.2516472-5-ben.widawsky@intel.com> References: <20210902195017.2516472-1-ben.widawsky@intel.com> <20210902195017.2516472-5-ben.widawsky@intel.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; i686-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.52.121.127] X-ClientProxiedBy: lhreml703-chm.china.huawei.com (10.201.108.52) To lhreml710-chm.china.huawei.com (10.201.108.61) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-cxl@vger.kernel.org On Thu, 2 Sep 2021 12:50:08 -0700 Ben Widawsky wrote: > Endpoints have decoders too. It is useful to share the same > infrastructure from cxl_core. Endpoints do not have dports (downstream > targets), only the underlying physical medium. As a result, some special > casing is needed. > > There is no functional change introduced yet as endpoints don't actually > enumerate decoders yet. > > Signed-off-by: Ben Widawsky Comments inline... > --- > drivers/cxl/core/bus.c | 29 +++++++++++++++++++++++++---- > 1 file changed, 25 insertions(+), 4 deletions(-) > > diff --git a/drivers/cxl/core/bus.c b/drivers/cxl/core/bus.c > index 8d5061b0794d..6202ce5a5ac2 100644 > --- a/drivers/cxl/core/bus.c > +++ b/drivers/cxl/core/bus.c > @@ -175,6 +175,12 @@ static const struct attribute_group *cxl_decoder_switch_attribute_groups[] = { > NULL, > }; > > +static const struct attribute_group *cxl_decoder_endpoint_attribute_groups[] = { > + &cxl_decoder_base_attribute_group, > + &cxl_base_attribute_group, > + NULL, > +}; > + > static void cxl_decoder_release(struct device *dev) > { > struct cxl_decoder *cxld = to_cxl_decoder(dev); > @@ -184,6 +190,12 @@ static void cxl_decoder_release(struct device *dev) > kfree(cxld); > } > > +static const struct device_type cxl_decoder_endpoint_type = { > + .name = "cxl_decoder_endpoint", > + .release = cxl_decoder_release, > + .groups = cxl_decoder_endpoint_attribute_groups, > +}; > + > static const struct device_type cxl_decoder_switch_type = { > .name = "cxl_decoder_switch", > .release = cxl_decoder_release, > @@ -196,6 +208,11 @@ static const struct device_type cxl_decoder_root_type = { > .groups = cxl_decoder_root_attribute_groups, > }; > > +static bool is_endpoint_decoder(struct device *dev) > +{ > + return dev->type == &cxl_decoder_endpoint_type; > +} > + > bool is_root_decoder(struct device *dev) > { > return dev->type == &cxl_decoder_root_type; > @@ -472,7 +489,7 @@ struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port, int nr_targets) > struct device *dev; > int rc = 0; > > - if (nr_targets > CXL_DECODER_MAX_INTERLEAVE || nr_targets < 1) Why do we let nr_targets go negative? Could make the parameter unsigned perhaps or check for that here (even though it makes no sense). > + if (nr_targets > CXL_DECODER_MAX_INTERLEAVE) > return ERR_PTR(-EINVAL); > > cxld = kzalloc(struct_size(cxld, target, nr_targets), GFP_KERNEL); > @@ -491,8 +508,11 @@ struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port, int nr_targets) > dev->parent = &port->dev; > dev->bus = &cxl_bus_type; > > + /* Endpoints don't have a target list */ > + if (nr_targets == 0) > + dev->type = &cxl_decoder_endpoint_type; Hmm. Whilst the check seems valid, it's a bit inelegant. The capability register unhelpfully simply has it defined as not applicable rather than 0, so I'd be nervous that might end up here (not checked yet). > /* root ports do not have a cxl_port_type parent */ > - if (port->dev.parent->type == &cxl_port_type) > + else if (port->dev.parent->type == &cxl_port_type) > dev->type = &cxl_decoder_switch_type; > else > dev->type = &cxl_decoder_root_type; > @@ -532,9 +552,11 @@ int cxl_decoder_add(struct device *host, struct cxl_decoder *cxld, > if (IS_ERR(cxld)) > return PTR_ERR(cxld); > > + dev = &cxld->dev; > + > port = to_cxl_port(cxld->dev.parent); > device_lock(&port->dev); > - if (list_empty(&port->dports)) { > + if (is_endpoint_decoder(dev) && list_empty(&port->dports)) { > rc = -EINVAL; > goto out_unlock; > } > @@ -551,7 +573,6 @@ int cxl_decoder_add(struct device *host, struct cxl_decoder *cxld, > } > device_unlock(&port->dev); > > - dev = &cxld->dev; > rc = dev_set_name(dev, "decoder%d.%d", port->id, cxld->id); > if (rc) > return rc;