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=-13.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 35BE4C433F5 for ; Mon, 13 Sep 2021 22:07:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1445161056 for ; Mon, 13 Sep 2021 22:07:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244386AbhIMWJM (ORCPT ); Mon, 13 Sep 2021 18:09:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39456 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234740AbhIMWJL (ORCPT ); Mon, 13 Sep 2021 18:09:11 -0400 Received: from mail-pj1-x102e.google.com (mail-pj1-x102e.google.com [IPv6:2607:f8b0:4864:20::102e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D0E9AC061574 for ; Mon, 13 Sep 2021 15:07:55 -0700 (PDT) Received: by mail-pj1-x102e.google.com with SMTP id f3-20020a17090a638300b00199097ddf1aso593031pjj.0 for ; Mon, 13 Sep 2021 15:07:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=DlCsUMDE2tScoyh2sgbiu/s0d/iESIMMXI3Fp/NGUoI=; b=AIgR+0DRKYbfsCS7r8Vpil92rxvvGmOnTqUzN7mdKvabaNsmMouel31t18w94F0o6B j3/WTKJ+rO2Kd9kIwnX0qcNeAGxSsEJ/SaaEgL9XEbjQZFFPcCB3A7QLsEb6ixDi0z5S u8Q7bLYWXMVBTTI88qhOPkTdiCr9nFrOeDqE229ozyzsEFuPU0WiPIHsS3LjSO8qQzWn eXxT2K4Zl6dy0AYQRf9uPRHj1BeoWECMo0iRxaaDr9r99jWPdvF3/jZKOjIPBNrLPQMM Ljenv5qdfBMvO/RiT/VJrpGeG9bl+ftLlua3CNmUrCggjbfBJ7GJIboFnrsSagrf96bI Nyeg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=DlCsUMDE2tScoyh2sgbiu/s0d/iESIMMXI3Fp/NGUoI=; b=hPFuPPgoEAYQ2d1P51gStOh5MIPl81knMt9gW2Jmz3Q1UWtGnw9CUQi8/itY3Mho7+ r/eKcZbjKuX+M78Ey8ZHvKVl/9eV08xTulFPJE18D5u6xQMDUrvjuLRdoIxxjmuC9k7P /fiUwEBbTVmKK/Z1tdJE2BhlgE4AD+Glr3hSeJFjz5xoeTooYtYLzwOSeKhalgehknFt ftSHIVgMgEk7ZBeqbJwuNg0DPcbfoA9NhCpwIC+P8JLJg+vgfrLI21aIEzkm+nCWRuPt 27Mjfz+sJ/PdMtWe6QBMjrM5VIBe8aHvS7cOjLyL08VzXWybT74pGDu78UGcxpbLQusb ozeQ== X-Gm-Message-State: AOAM532fZoNXjVSezhlvwu+ZHWxi5yqJ368e6K1zm7QJ7YAx8geJczw1 qf+LFCF02YfvPNOWbIJwc0l8oep+QaTO5dk8usQSkY+r+Lc= X-Google-Smtp-Source: ABdhPJyBnGE9w4694UHcx6kw/Hn4gbcPayctc58CEgWAmZGxH16RUH3i6Lp8AalDCB/hOaE+czqlesCSSC1UMO1Cc7w= X-Received: by 2002:a17:902:bd8d:b0:13a:8c8:a2b2 with SMTP id q13-20020a170902bd8d00b0013a08c8a2b2mr12335461pls.89.1631570875348; Mon, 13 Sep 2021 15:07:55 -0700 (PDT) MIME-Version: 1.0 References: <20210902195017.2516472-1-ben.widawsky@intel.com> <20210902195017.2516472-5-ben.widawsky@intel.com> <20210913161149.ggbd5jmro2davaq5@intel.com> In-Reply-To: <20210913161149.ggbd5jmro2davaq5@intel.com> From: Dan Williams Date: Mon, 13 Sep 2021 15:07:44 -0700 Message-ID: Subject: Re: [PATCH 04/13] cxl: Introduce endpoint decoders To: Ben Widawsky Cc: linux-cxl@vger.kernel.org, Alison Schofield , Ira Weiny , Jonathan Cameron , Vishal Verma Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-cxl@vger.kernel.org On Mon, Sep 13, 2021 at 9:11 AM Ben Widawsky wrote: > > On 21-09-10 12:19:24, Dan Williams wrote: > > On Thu, Sep 2, 2021 at 12:50 PM 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 > > > --- > > > 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) > > > + 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; > > > > Do you also plan to introduce the concept of endpoint ports, and if > > yes should that come before this patch? That would seem to be more > > robust than, for example, allowing a switch port to carry an endpoint > > decoder object as this allows. > > I didn't see a need as of yet to differentiate between endpoint ports and other > ports. I don't entirely understand what you mean by "allowing a switch port to > carry an endpoint decoder" means. Can you please elaborate? If endpoint ports were an explicit type then this check could make sure that someone did not pass nr_targets set to 0 where the @port argument is referring to a switch where the target_list must be specified. Either that, or a comment in kernel-doc for this routine about the special meaning of nr_targets == 0 and expected usage.