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=-0.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 679B3C04AB1 for ; Thu, 9 May 2019 14:02:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3E8C72053B for ; Thu, 9 May 2019 14:02:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726590AbfEIOCZ convert rfc822-to-8bit (ORCPT ); Thu, 9 May 2019 10:02:25 -0400 Received: from mx2.suse.de ([195.135.220.15]:57984 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726597AbfEIOCY (ORCPT ); Thu, 9 May 2019 10:02:24 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id DDBE4AC70; Thu, 9 May 2019 14:02:21 +0000 (UTC) Date: Thu, 9 May 2019 16:02:20 +0200 From: Thomas Bogendoerfer To: Lee Jones Cc: Ralf Baechle , Paul Burton , James Hogan , Dmitry Torokhov , "David S. Miller" , Alessandro Zummo , Alexandre Belloni , Greg Kroah-Hartman , Jiri Slaby , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, linux-input@vger.kernel.org, netdev@vger.kernel.org, linux-rtc@vger.kernel.org, linux-serial@vger.kernel.org Subject: Re: [PATCH v2 2/4] mfd: ioc3: Add driver for SGI IOC3 chip Message-Id: <20190509160220.bb5382df931e5bd0972276df@suse.de> In-Reply-To: <20190508102313.GG3995@dell> References: <20190409154610.6735-1-tbogendoerfer@suse.de> <20190409154610.6735-3-tbogendoerfer@suse.de> <20190508102313.GG3995@dell> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-suse-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-rtc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org On Wed, 8 May 2019 11:23:13 +0100 Lee Jones wrote: > On Tue, 09 Apr 2019, Thomas Bogendoerfer wrote: > > > +static u32 crc8_addr(u64 addr) > > +{ > > + u32 crc = 0; > > + int i; > > + > > + for (i = 0; i < 64; i += 8) > > + crc8_byte(&crc, addr >> i); > > + return crc; > > +} > > Not looked into these in any detail, but are you not able to use the > CRC functions already provided by the kernel? they are using a different polynomial, so I can't use it. > > + } > > + pr_err("ioc3: CRC error in NIC address\n"); > > +} > > This all looks like networking code. If this is the case, it should > be moved to drivers/networking or similar. no it's not. nic stands for number in a can produced by Dallas Semi also known under the name 1-Wire (https://en.wikipedia.org/wiki/1-Wire). SGI used them to provide partnumber, serialnumber and mac addresses. By placing the code to read the NiCs inside ioc3 driver there is no need for locking and adding library code for accessing these informations. > > +static struct resource ioc3_uarta_resources[] = { > > + DEFINE_RES_MEM(offsetof(struct ioc3, sregs.uarta), > > You are the first user of offsetof() in MFD. Could you tell me why > it's required please? to get the offsets of different chip functions out of a struct. > Please drop all of these and statically create the MFD cells like > almost all other MFD drivers do. I started that way and it blew up the driver and create a bigger mess than I wanted to have. What's your concern with my approach ? I could use static mfd_cell arrays, if there would be a init/startup method per cell, which is called before setting up the platform device. That way I could do the dynamic setup for ethernet and serial devices. > > +static void ioc3_create_devices(struct ioc3_priv_data *ipd) > > +{ > > + struct mfd_cell *cell; > > + > > + memset(ioc3_mfd_cells, 0, sizeof(ioc3_mfd_cells)); > > + cell = ioc3_mfd_cells; > > + > > + if (ipd->info->funcs & IOC3_ETH) { > > + memcpy(ioc3_eth_platform_data.mac_addr, ipd->nic_mac, > > + sizeof(ioc3_eth_platform_data.mac_addr)); > > Better to pull the MAC address from within the Ethernet driver. the NiC where the MAC address is provided is connected to the ioc3 chip outside of the ethernet register set. And there is another NiC connected to the same 1-W bus. So moving reading of the MAC address to the ethernet driver duplicates code and adds complexity (locking). Again what's your concern here ? > > + if (ipd->info->funcs & IOC3_SER) { > > + writel(GPCR_UARTA_MODESEL | GPCR_UARTB_MODESEL, > > + &ipd->regs->gpcr_s); > > + writel(0, &ipd->regs->gppr[6]); > > + writel(0, &ipd->regs->gppr[7]); > > + udelay(100); > > + writel(readl(&ipd->regs->port_a.sscr) & ~SSCR_DMA_EN, > > + &ipd->regs->port_a.sscr); > > + writel(readl(&ipd->regs->port_b.sscr) & ~SSCR_DMA_EN, > > + &ipd->regs->port_b.sscr); > > + udelay(1000); > > No idea what any of this does. > > It looks like it belongs in the serial driver (and needs comments). it configures the IOC3 chip for serial usage. This is not part of the serial register set, so it IMHO belongs in the MFD driver. > > + } > > +#if defined(CONFIG_SGI_IP27) > > What is this? Can't you obtain this dynamically by probing the H/W? that's the machine type and the #ifdef CONFIG_xxx are just for saving space, when compiled for other machines and it's easy to remove. > > + if (ipd->info->irq_offset) { > > What does this really signify? IOC3 ASICs are most of the time connected to a SGI bridge chip. IOC3 can provide two interrupt lines, which are wired to the bridge chip. The first interrupt is assigned via the PCI core, but since IOC3 is not a PCI multi function device the second interrupt must be treated here. And the used interrupt line on the bridge chip differs between boards. Thank you for your review. I'll address all other comments not cited in my mail. Thomas. -- SUSE Linux GmbH GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 21284 (AG Nürnberg)