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 6CAB5C433EF for ; Mon, 22 Nov 2021 16:20:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240217AbhKVQXu (ORCPT ); Mon, 22 Nov 2021 11:23:50 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]:4138 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240080AbhKVQXt (ORCPT ); Mon, 22 Nov 2021 11:23:49 -0500 Received: from fraeml703-chm.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4HyXTY6Jrkz67KMD; Tue, 23 Nov 2021 00:16:49 +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 15.1.2308.20; Mon, 22 Nov 2021 17:20:40 +0100 Received: from localhost (10.202.226.41) 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 15.1.2308.20; Mon, 22 Nov 2021 16:20:40 +0000 Date: Mon, 22 Nov 2021 16:20:39 +0000 From: Jonathan Cameron To: Ben Widawsky CC: , , "Alison Schofield" , Dan Williams , Ira Weiny , Vishal Verma Subject: Re: [PATCH 12/23] cxl: Introduce endpoint decoders Message-ID: <20211122162039.000022c1@Huawei.com> In-Reply-To: <20211120000250.1663391-13-ben.widawsky@intel.com> References: <20211120000250.1663391-1-ben.widawsky@intel.com> <20211120000250.1663391-13-ben.widawsky@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: [10.202.226.41] X-ClientProxiedBy: lhreml737-chm.china.huawei.com (10.201.108.187) To lhreml710-chm.china.huawei.com (10.201.108.61) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Fri, 19 Nov 2021 16:02:39 -0800 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 I'm not a fan of special values like using 0 here to indicate endpoint device. I'd rather see a base cxl_decode_alloc(..., bool ep) and possibly wrappers for the non ep case and ep one. Jonathan > --- > drivers/cxl/core/bus.c | 41 +++++++++++++++++++++++++++++++++-------- > 1 file changed, 33 insertions(+), 8 deletions(-) > > diff --git a/drivers/cxl/core/bus.c b/drivers/cxl/core/bus.c > index 1ee12a60f3f4..16b15f54fb62 100644 > --- a/drivers/cxl/core/bus.c > +++ b/drivers/cxl/core/bus.c > @@ -187,6 +187,12 @@ 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); > @@ -196,6 +202,12 @@ 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, > @@ -208,6 +220,11 @@ 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; > @@ -499,7 +516,9 @@ static int decoder_populate_targets(struct cxl_decoder *cxld, > * cxl_decoder_alloc - Allocate a new CXL decoder > * @port: owning port of this decoder > * @nr_targets: downstream targets accessible by this decoder. All upstream > - * ports and root ports must have at least 1 target. > + * ports and root ports must have at least 1 target. Endpoint > + * devices will have 0 targets. Callers wishing to register an > + * endpoint device should specify 0. > * > * A port should contain one or more decoders. Each of those decoders enable > * some address space for CXL.mem utilization. A decoder is expected to be > @@ -516,7 +535,7 @@ struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port, > struct device *dev; > int rc = 0; > > - if (nr_targets > CXL_DECODER_MAX_INTERLEAVE || nr_targets == 0) > + if (nr_targets > CXL_DECODER_MAX_INTERLEAVE) > return ERR_PTR(-EINVAL); > > cxld = kzalloc(struct_size(cxld, target, nr_targets), GFP_KERNEL); > @@ -535,8 +554,11 @@ struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port, > 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; > /* 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; > @@ -579,12 +601,15 @@ int cxl_decoder_add(struct cxl_decoder *cxld, int *target_map) > if (cxld->interleave_ways < 1) > return -EINVAL; > > - port = to_cxl_port(cxld->dev.parent); > - rc = decoder_populate_targets(cxld, port, target_map); > - if (rc) > - return rc; > - > dev = &cxld->dev; > + > + port = to_cxl_port(cxld->dev.parent); > + if (!is_endpoint_decoder(dev)) { > + rc = decoder_populate_targets(cxld, port, target_map); > + if (rc) > + return rc; > + } > + > rc = dev_set_name(dev, "decoder%d.%d", port->id, cxld->id); > if (rc) > return rc;