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=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 3B1DAC433E4 for ; Mon, 18 May 2020 10:10:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 247D7206D4 for ; Mon, 18 May 2020 10:10:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726341AbgERKKY (ORCPT ); Mon, 18 May 2020 06:10:24 -0400 Received: from mail-oi1-f194.google.com ([209.85.167.194]:42086 "EHLO mail-oi1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726040AbgERKKY (ORCPT ); Mon, 18 May 2020 06:10:24 -0400 Received: by mail-oi1-f194.google.com with SMTP id l6so2622638oic.9; Mon, 18 May 2020 03:10:22 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=OUWwAW1tiZj2X0S32FYVRQZMXC7D2eYX5NkiVFQhWuM=; b=jHTzn0kZ2WgWP9ll68PeWpOYW0SEYTSqGrXDFO8PGseYmiIfoWTSpXlLyYJy29CYQW dNTCM+K5gIbTai1adyeqFkkIUyK6mzuwE+jH/ePsJML9KoSW0vxr+fIC++q68ovb4/00 8kqWB5arem5HInZB92P9a92Qj0JRRNkbgmXDRodzeQiHzCdAADtw63Z+ok2mBV6RQkM8 e8VieaBLvO150B/p2z0MWWNTGRBBekAxuY3bPm5TshYCw5Hw16GpgDLgXcQ6uXINA4JQ u2ou/Ffsot0kaRARMOuGS6vqLAMx4yh2PpNrmTW4MAqIjRKoCH9FCFQH9+uo//o1vmaL c0mg== X-Gm-Message-State: AOAM532JzgILyyQvEpVz1AHJaQQhr5gOPcJ7DhZc82wPHXEqNs3k1lPq 839j7oyD3Uk8nSgXatxWR08i2UanzBUJBKeOfwQ= X-Google-Smtp-Source: ABdhPJyBWPgZF8Nef5VFnPwIMZCFFtRvCnBOgZddEawH+Whlxj+gaH+OLdK5CmIFCwYF6ugC0lIB1QUdlxdAkaabczY= X-Received: by 2002:aca:cd93:: with SMTP id d141mr9870659oig.148.1589796621997; Mon, 18 May 2020 03:10:21 -0700 (PDT) MIME-Version: 1.0 References: <1589555337-5498-1-git-send-email-prabhakar.mahadev-lad.rj@bp.renesas.com> <1589555337-5498-4-git-send-email-prabhakar.mahadev-lad.rj@bp.renesas.com> <20200515171031.GB19423@ninjato> <20200518092601.GA3268@ninjato> In-Reply-To: <20200518092601.GA3268@ninjato> From: Geert Uytterhoeven Date: Mon, 18 May 2020 12:10:05 +0200 Message-ID: Subject: Re: [PATCH 03/17] ARM: dts: r8a7742: Add I2C and IIC support To: Wolfram Sang Cc: "Lad, Prabhakar" , Lad Prabhakar , Jens Axboe , Rob Herring , Ulf Hansson , Sergei Shtylyov , "David S. Miller" , Wim Van Sebroeck , Guenter Roeck , linux-ide@vger.kernel.org, "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , LKML , Linux I2C , Linux MMC List , netdev , Linux-Renesas , Linux Watchdog Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-ide-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ide@vger.kernel.org Hi Wolfram, On Mon, May 18, 2020 at 11:26 AM Wolfram Sang wrote: > > > However, both versions (with and without automatic transmission) are > > > described with the same "renesas,iic-r8a7742" compatible. Is it possible > > > to detect the reduced variant at runtime somehow? > > > > > I couldn't find anything the manual that would be useful to detect at runtime. Hence if we really need that (see below), we need a quirk based on compatible value + base address. > > > My concern is that the peculiarity of this SoC might be forgotten if we > > > describe it like this and ever add "automatic transmissions" somewhen. > > > > > Agreed. > > Well, I guess reading from a register which is supposed to not be there > on the modified IP core is too hackish. According to the Hardware User's Manual Rev. 1.00, the registers do exist on all RZ/G1, except for RZ/G1E (see below). "(automatic transmission can be used as a hardware function, but this is not meaningful for actual use cases)." (whatever that comment may mean?) > Leaves us with a seperate compatible entry for it? On R-Car E3 and RZ/G2E, which have a single IIC instance, we handled that by: The r8a77990 (R-Car E3) and r8a774c0 (RZ/G2E) controllers are not considered compatible with "renesas,rcar-gen3-iic" or "renesas,rmobile-iic" due to the absence of automatic transmission registers. On R-Car E2 and RZ/G1E, we forgot, and used both SoC-specific and family-specific compatible values. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds