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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_MED, 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 6C2BBC433F4 for ; Mon, 27 Aug 2018 08:56:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1F95A20835 for ; Mon, 27 Aug 2018 08:56:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=bgdev-pl.20150623.gappssmtp.com header.i=@bgdev-pl.20150623.gappssmtp.com header.b="0FtmzQCW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1F95A20835 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bgdev.pl Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727193AbeH0MmQ (ORCPT ); Mon, 27 Aug 2018 08:42:16 -0400 Received: from mail-io0-f195.google.com ([209.85.223.195]:41647 "EHLO mail-io0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726785AbeH0MmP (ORCPT ); Mon, 27 Aug 2018 08:42:15 -0400 Received: by mail-io0-f195.google.com with SMTP id q4-v6so12203988iob.8 for ; Mon, 27 Aug 2018 01:56:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bgdev-pl.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=h4PZMzainKCYUvAYL5kM5LaaqKl+5u8AZLn6hSJrix0=; b=0FtmzQCW1PGXrhMXm6Y7OdfrHTI0+Gc/ahaFiGa2H4XnqrgKjyQ5mxGfT40yx2RaaT smJgKBS8ue1EOq5h3CwnZ47UjCWj1i28rtNn8kaO2c8/bNDO0VKU/9Rl+h9F8lKXBAhk +tRYCEPfE6J8KTVXqF3SypX+8UMVRitchO9YDxGp4as/bkwhbyKtVAoC8srUoi0oce77 ezHQNNi7IQqGSj7683HHKFT8YPZ+2YnjXCSbcRyrv0I3FQSHsTgQjTRTn+9VcPBxwuHr tXyze0RfpaHtqfAZwQppqgl6IhSuGHzWjoL0JpbKF0sgT8pN4mF7HSaEYf9gE5HkathW lLOg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=h4PZMzainKCYUvAYL5kM5LaaqKl+5u8AZLn6hSJrix0=; b=eL5PYgK6VCGZ6H047zlKdDNBcHo/WAGJ7R3a5T/6Ca6d9rz2baUaEunHB9ft0Ly6Y4 xc71pJVvkfLXiBICBdv9sgEY2hDEw8xX7WIVBf6v+WFRtNSC2XT43FHKIjb0k89GXzus 2UHnv1tR0L68zx2jYCGnKFq+M94k6M1alAU9DrdEd/aC2Ybzo1LXTZACZ/ctnQBAn3q8 vgwiPLNfb+lLfeowE1XuoLZCOQ3MwTrVGyD8FPeOcUV4C6liAErxUlmbsfv8MupBZFn9 hM8ETmul4L4I+NgrZEX0uCcjMz/DQl5VpmRKd1RUbBkDO3rZMtfBa+2wsdkoBPd+CTMN lNPA== X-Gm-Message-State: APzg51Bf5RVRVHyYeuJgUZ+tkhhGUiRLD+5RClYW6zuFH8+YPtEmkk+K s0NCRQUbolWqfHOnXjC1k+MlGNrBUR5bkN4H6q9f8A== X-Google-Smtp-Source: ANB0VdZU1O7YL3J3GW+L5yGErVWtcVknMMAbt3xIXjNATiQ5ffLroUoMphXiVYhg07HumLojqYn5ubFQjWIf10YpXtw= X-Received: by 2002:a5e:8d07:: with SMTP id m7-v6mr9209179ioj.258.1535360190362; Mon, 27 Aug 2018 01:56:30 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a5e:9402:0:0:0:0:0 with HTTP; Mon, 27 Aug 2018 01:56:29 -0700 (PDT) In-Reply-To: <20180825082722.567e8c9a@bbrezillon> References: <20180810080526.27207-1-brgl@bgdev.pl> <20180810080526.27207-2-brgl@bgdev.pl> <20180824170848.29594318@bbrezillon> <20180824152740.GD27483@lunn.ch> <20180825082722.567e8c9a@bbrezillon> From: Bartosz Golaszewski Date: Mon, 27 Aug 2018 10:56:29 +0200 Message-ID: Subject: Re: [PATCH v2 01/29] nvmem: add support for cell lookups To: Boris Brezillon Cc: Andrew Lunn , linux-doc , Sekhar Nori , Bartosz Golaszewski , Srinivas Kandagatla , linux-i2c , Mauro Carvalho Chehab , Rob Herring , Florian Fainelli , Kevin Hilman , Richard Weinberger , Russell King , Marek Vasut , Paolo Abeni , Dan Carpenter , Grygorii Strashko , David Lechner , Arnd Bergmann , Sven Van Asbroeck , "open list:MEMORY TECHNOLOGY..." , Linux-OMAP , Linux ARM , Ivan Khoronzhuk , Greg Kroah-Hartman , Jonathan Corbet , Linux Kernel Mailing List , Lukas Wunner , Naren , netdev , Alban Bedel , Andrew Morton , Brian Norris , David Woodhouse , "David S . Miller" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2018-08-25 8:27 GMT+02:00 Boris Brezillon : > On Fri, 24 Aug 2018 17:27:40 +0200 > Andrew Lunn wrote: > >> On Fri, Aug 24, 2018 at 05:08:48PM +0200, Boris Brezillon wrote: >> > Hi Bartosz, >> > >> > On Fri, 10 Aug 2018 10:04:58 +0200 >> > Bartosz Golaszewski wrote: >> > >> > > +struct nvmem_cell_lookup { >> > > + struct nvmem_cell_info info; >> > > + struct list_head list; >> > > + const char *nvmem_name; >> > > +}; >> > >> > Hm, maybe I don't get it right, but this looks suspicious. Usually the >> > consumer lookup table is here to attach device specific names to >> > external resources. >> > >> > So what I'd expect here is: >> > >> > struct nvmem_cell_lookup { >> > /* The nvmem device name. */ >> > const char *nvmem_name; >> > >> > /* The nvmem cell name */ >> > const char *nvmem_cell_name; >> > >> > /* >> > * The local resource name. Basically what you have in the >> > * nvmem-cell-names prop. >> > */ >> > const char *conid; >> > }; >> > >> > struct nvmem_cell_lookup_table { >> > struct list_head list; >> > >> > /* ID of the consumer device. */ >> > const char *devid; >> > >> > /* Array of cell lookup entries. */ >> > unsigned int ncells; >> > const struct nvmem_cell_lookup *cells; >> > }; >> > >> > Looks like your nvmem_cell_lookup is more something used to attach cells >> > to an nvmem device, which is NVMEM provider's responsibility not the >> > consumer one. >> >> Hi Boris >> >> There are cases where there is not a clear providier/consumer split. I >> have an x86 platform, with a few at24 EEPROMs on it. It uses an off >> the shelf Komtron module, placed on a custom carrier board. One of the >> EEPROMs contains the hardware variant information. Once i know the >> variant, i need to instantiate other I2C, SPI, MDIO devices, all using >> platform devices, since this is x86, no DT available. >> >> So the first thing my x86 platform device does is instantiate the >> first i2c device for the AT24. Once the EEPROM pops into existence, i >> need to add nvmem cells onto it. So at that point, the x86 platform >> driver is playing the provider role. Once the cells are added, i can >> then use nvmem consumer interfaces to get the contents of the cell, >> run a checksum, and instantiate the other devices. >> >> I wish the embedded world was all DT, but the reality is that it is >> not :-( > > Actually, I'm not questioning the need for this feature (being able to > attach NVMEM cells to an NVMEM device on a platform that does not use > DT). What I'm saying is that this functionality is provider related, > not consumer related. Also, I wonder if defining such NVMEM cells > shouldn't go through the provider driver instead of being passed > directly to the NVMEM layer, because nvmem_config already have a fields > to pass cells at registration time, plus, the name of the NVMEM cell > device is sometimes created dynamically and can be hard to guess at > platform_device registration time. > In my use case the provider is at24 EEPROM driver. This is where the nvmem_config lives but I can't image a correct and clean way of passing this cell config to the driver from board files without using new ugly fields in platform_data which this very series is trying to remove. This is why this cell config should live in machine code. > I also think non-DT consumers will need a way to reference exiting > NVMEM cells, but this consumer-oriented nvmem cell lookup table should > look like the gpio or pwm lookup table (basically what I proposed in my > previous email). How about introducing two new interfaces to nvmem: one for defining nvmem cells from machine code and the second for connecting these cells with devices? Best regards, Bart