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 3363EC433EF for ; Mon, 22 Nov 2021 19:37:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239773AbhKVTlB (ORCPT ); Mon, 22 Nov 2021 14:41:01 -0500 Received: from mga12.intel.com ([192.55.52.136]:35172 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231856AbhKVTlA (ORCPT ); Mon, 22 Nov 2021 14:41:00 -0500 X-IronPort-AV: E=McAfee;i="6200,9189,10176"; a="214890335" X-IronPort-AV: E=Sophos;i="5.87,255,1631602800"; d="scan'208";a="214890335" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Nov 2021 11:37:53 -0800 X-IronPort-AV: E=Sophos;i="5.87,255,1631602800"; d="scan'208";a="456764356" Received: from wqiu6-mobl.amr.corp.intel.com (HELO intel.com) ([10.252.143.45]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Nov 2021 11:37:52 -0800 Date: Mon, 22 Nov 2021 11:37:51 -0800 From: Ben Widawsky To: Jonathan Cameron Cc: linux-cxl@vger.kernel.org, linux-pci@vger.kernel.org, Alison Schofield , Dan Williams , Ira Weiny , Vishal Verma Subject: Re: [PATCH 12/23] cxl: Introduce endpoint decoders Message-ID: <20211122193751.gipqgs5ap24dacm3@intel.com> References: <20211120000250.1663391-1-ben.widawsky@intel.com> <20211120000250.1663391-13-ben.widawsky@intel.com> <20211122162039.000022c1@Huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211122162039.000022c1@Huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-cxl@vger.kernel.org On 21-11-22 16:20:39, Jonathan Cameron wrote: > 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 > My inclination is the opposite. However, I think you and Dan both brought up something to this effect in the previous RFCs. Dan, do you have a preference here? > > --- > > 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; >