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 1BC42CA0FE8 for ; Fri, 1 Sep 2023 09:07:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245739AbjIAJH0 (ORCPT ); Fri, 1 Sep 2023 05:07:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37250 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238270AbjIAJHY (ORCPT ); Fri, 1 Sep 2023 05:07:24 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AAC3B10D2; Fri, 1 Sep 2023 02:07:17 -0700 (PDT) Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4RcXF70gkKz6HJgB; Fri, 1 Sep 2023 17:05:47 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Fri, 1 Sep 2023 10:06:54 +0100 Date: Fri, 1 Sep 2023 10:06:54 +0100 From: Jonathan Cameron To: Robert Richter CC: Terry Bowman , , , , , , , , , Subject: Re: [PATCH v9 01/15] cxl/port: Pre-initialize component register mappings Message-ID: <20230901100654.00006799@Huawei.com> In-Reply-To: References: <20230825233211.3029825-1-terry.bowman@amd.com> <20230825233211.3029825-2-terry.bowman@amd.com> <20230829143851.00006467@Huawei.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml500006.china.huawei.com (7.191.161.198) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 31 Aug 2023 14:22:35 +0200 Robert Richter wrote: > On 29.08.23 14:38:51, Jonathan Cameron wrote: > > On Fri, 25 Aug 2023 18:31:57 -0500 > > Terry Bowman wrote: > > > > > From: Robert Richter > > > > Hi Robert, Terry, > > > > > > > > The component registers of a component may not exist or are not > > > needed. > > > > How do we now it's not needed in this function? > > Perhaps "may not exist." is the bit that matters in this sentence. > > > > > The setup may fail for that reason. In some cases the > > > initialization should continue anyway. Thus, always initialize struct > > > cxl_register_map with valid values. In case of errors, zero it, set a > > > value for @dev and make @resource a the valid value using > > > > make @resource CXL_RESOURCE_NONE. > > > > (not "a the") > > > > > CXL_RESOURCE_NONE. > > > > It might be worth making it clear that this will (I think) only matter > > for future usecases and isn't a fix for how this function is used today. > > I reworded the whole text: > > """ > The component registers of a component may not exist and > cxl_setup_comp_regs() will fail for that reason. In another case, > Software may not use and set those registers up. cxl_setup_comp_regs() > is then called with a base address of CXL_RESOURCE_NONE. Both are > valid cases, but the function returns without initializing the > register map. > > Now, a missing component register block is not necessarily a reason to > fail (feature is optional or its existence checked later). Change > cxl_setup_comp_regs() to also use components with the component > register block missing. Thus, always initialize struct > cxl_register_map with valid values, set @dev and make @resource > CXL_RESOURCE_NONE. > > The change is in preparation of follow-on patches. > """ Looks good to me. J > > I hope that is better now. > > > > > > > > > Signed-off-by: Robert Richter > > > Signed-off-by: Terry Bowman > > Otherwise seems sensible to me with one comment below. > > > > Reviewed-by: Jonathan Cameron > > > > > --- > > > drivers/cxl/core/port.c | 11 ++++++----- > > > 1 file changed, 6 insertions(+), 5 deletions(-) > > > > > > diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c > > > index 724be8448eb4..2d22e7a5629b 100644 > > > --- a/drivers/cxl/core/port.c > > > +++ b/drivers/cxl/core/port.c > > > @@ -693,16 +693,17 @@ static struct cxl_port *cxl_port_alloc(struct device *uport_dev, > > > static int cxl_setup_comp_regs(struct device *dev, struct cxl_register_map *map, > > > resource_size_t component_reg_phys) > > > { > > > - if (component_reg_phys == CXL_RESOURCE_NONE) > > > - return 0; > > > - > > > *map = (struct cxl_register_map) { > > > .dev = dev, > > > - .reg_type = CXL_REGLOC_RBI_COMPONENT, > > > > Could set this explicitly to CXL_REGLOC_RBI_EMPTY > > which is what happens anyway, but it isn't obvious that > > 0 maps to something that indicates this doesn't exist. > > Will change that. > > Thanks, > > -Robert > > > > > > > .resource = component_reg_phys, > > > - .max_size = CXL_COMPONENT_REG_BLOCK_SIZE, > > > }; > > > > > > + if (component_reg_phys == CXL_RESOURCE_NONE) > > > + return 0; > > > + > > > + map->reg_type = CXL_REGLOC_RBI_COMPONENT; > > > + map->max_size = CXL_COMPONENT_REG_BLOCK_SIZE; > > > + > > > return cxl_setup_regs(map); > > > } > > > > >