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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 C061FC433DB for ; Fri, 8 Jan 2021 07:47:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 767CF2343B for ; Fri, 8 Jan 2021 07:47:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727449AbhAHHrr (ORCPT ); Fri, 8 Jan 2021 02:47:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:50656 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726027AbhAHHrr (ORCPT ); Fri, 8 Jan 2021 02:47:47 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 890D2233EE; Fri, 8 Jan 2021 07:47:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1610092026; bh=aht0WdMXCPlAoFq0DlnM+/6kealmxDfX0uEiia9bmxs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=vWX6roBwrJrKKoRl6iEtW14ixgMgYXomRcg1ExcRPNyoKh4jaMUzdTmnVkv3twW4R K4tZI0562rr6LGrnJsDAbETE6A3KH/48g+5EQE5YIbtnFSlc2SKf0h23QN9lr9REIj ufYwT6idwpnSKYBaT4VySvKkVo8f05E3UOJPueCc= Date: Fri, 8 Jan 2021 08:47:02 +0100 From: Greg KH To: Xu Yilun Cc: andrew@lunn.ch, arnd@arndb.de, lee.jones@linaro.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, trix@redhat.com, lgoncalv@redhat.com, hao.wu@intel.com, matthew.gerlach@intel.com, russell.h.weight@intel.com Subject: Re: [RESEND PATCH 2/2] misc: add support for retimers interfaces on Intel MAX 10 BMC Message-ID: References: <1609999628-12748-1-git-send-email-yilun.xu@intel.com> <1609999628-12748-3-git-send-email-yilun.xu@intel.com> <20210108020526.GB13860@yilunxu-OptiPlex-7050> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210108020526.GB13860@yilunxu-OptiPlex-7050> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 08, 2021 at 10:05:26AM +0800, Xu Yilun wrote: > On Thu, Jan 07, 2021 at 10:26:12AM +0100, Greg KH wrote: > > On Thu, Jan 07, 2021 at 02:07:08PM +0800, Xu Yilun wrote: > > > This driver supports the ethernet retimers (C827) for the Intel PAC > > > (Programmable Acceleration Card) N3000, which is a FPGA based Smart NIC. > > > > > > C827 is an Intel(R) Ethernet serdes transceiver chip that supports > > > up to 100G transfer. On Intel PAC N3000 there are 2 C827 chips > > > managed by the Intel MAX 10 BMC firmware. They are configured in 4 ports > > > 10G/25G retimer mode. Host could query their link states and firmware > > > version information via retimer interfaces (Shared registers) on Intel > > > MAX 10 BMC. The driver creates sysfs interfaces for users to query these > > > information. > > > > Networking people, please look at this sysfs file: > > > > > +What: /sys/bus/platform/devices/n3000bmc-retimer.*.auto/link_statusX > > > +Date: Jan 2021 > > > +KernelVersion: 5.12 > > > +Contact: Xu Yilun > > > +Description: Read only. Returns the status of each line side link. "1" for > > > + link up, "0" for link down. > > > + Format: "%u". > > > > as I need your approval to add it because it is not the "normal" way for > > link status to be exported to userspace. > > > > One code issue: > > > > > +#define to_link_attr(dev_attr) \ > > > + container_of(dev_attr, struct link_attr, attr) > > > + > > > +static ssize_t > > > +link_status_show(struct device *dev, struct device_attribute *attr, char *buf) > > > +{ > > > + struct m10bmc_retimer *retimer = dev_get_drvdata(dev); > > > + struct link_attr *lattr = to_link_attr(attr); > > > + unsigned int val; > > > + int ret; > > > + > > > + ret = m10bmc_sys_read(retimer->m10bmc, M10BMC_PKVL_LSTATUS, &val); > > > + if (ret) > > > + return ret; > > > + > > > + return sysfs_emit(buf, "%u\n", > > > + !!(val & BIT((retimer->id << 2) + lattr->index))); > > > +} > > > + > > > +#define link_status_attr(_index) \ > > > + static struct link_attr link_attr_status##_index = \ > > > + { .attr = __ATTR(link_status##_index, 0444, \ > > > + link_status_show, NULL), \ > > > + .index = (_index) } > > > > Why is this a "raw" attribute and not a device attribute? > > It is actually a device_attribute. The device_attribute is embedded in > link_attr, like: > > struct link_attr { > struct device_attribute attr; > u32 index; > }; > > An index for the link is appended along with the device_attribute, so we > could identify which link is being queried on link_status_show(). There > are 4 links and this is to avoid duplicated code like > link_status_1_show(), link_status_2_show() ... Duplicated code is better to read than complex code :) > > Please just use a normal DEVICE_ATTR_RO() macro to make it simpler and > > DEVICE_ATTR_RO() is to define a standalone device_attribute variable, but > here we are initializing a field in struct link_attr. Then use the correct initialization macro that is given to you for that, do not roll your own. greg k-h