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_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 30EC2C4321E for ; Mon, 10 Sep 2018 13:11:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CDFC2206BB for ; Mon, 10 Sep 2018 13:11:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CDFC2206BB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-m68k.org 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 S1728546AbeIJSF3 (ORCPT ); Mon, 10 Sep 2018 14:05:29 -0400 Received: from mail-vk0-f66.google.com ([209.85.213.66]:44250 "EHLO mail-vk0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727269AbeIJSF3 (ORCPT ); Mon, 10 Sep 2018 14:05:29 -0400 Received: by mail-vk0-f66.google.com with SMTP id 125-v6so259083vke.11; Mon, 10 Sep 2018 06:11:27 -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=NDg+dlr9c5bFJibqiT+fXGWyD22f9cgMHfDNhWtyXOU=; b=I3KfbGyFejQ3520ts1We47c7stqyqVEWTUM7G+qi3aMOxsmBT4nmP3PUXvqWqltWBn Jvj76CnnZDee2GC3XsVdEYeAChdJAt5xH+OCqUaoYsBBsnBJif6zwSg2ZWVLVLABzX97 7igcnnnu8/M9SjhFvqYfIy4IOswFyzZgxgGkJcu9BxrYBvegjqF+KiWl5OUlShoNuvYY w5Ue7E4u+s9WKtPKkC/IcYE2v3Ibo8HZm9xiKrInN6OgwvKl+ZHi+NCWx1Nw30bnpead GpYQAbYZ95dCDlFOp1nSykayr/S0oSgwNr1a9d7GO+QbJ8T/7rUsFj8OhSkzc1d75JFp o66w== X-Gm-Message-State: APzg51BNe1GaPcr9k3/6T2JHzc4Mn3qcL8ejW3YXi+a0grEPLtirfDkb dbMGn9KcDV+ZAzTuj5d0Kd55rvEjA9SHb+EMtpn/03/d X-Google-Smtp-Source: ANB0VdZbCz7q2FOlgSG4tyQMaftLcJLlp7LbivoIun+RXF2kJKZyLYiz6bo63NtTR8EFEFcxsyiuJLhSQuLHw/UjgAk= X-Received: by 2002:a1f:1246:: with SMTP id 67-v6mr6325456vks.82.1536585087190; Mon, 10 Sep 2018 06:11:27 -0700 (PDT) MIME-Version: 1.0 References: <1535714796-2211-1-git-send-email-phil.edworthy@renesas.com> In-Reply-To: <1535714796-2211-1-git-send-email-phil.edworthy@renesas.com> From: Geert Uytterhoeven Date: Mon, 10 Sep 2018 15:11:15 +0200 Message-ID: Subject: Re: [PATCH] clk: renesas: r9a06g032: Fix UART34567 clock rate To: Phil Edworthy Cc: Michael Turquette , Stephen Boyd , Linux-Renesas , linux-clk , Linux Kernel Mailing List 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 Hi Phil, On Fri, Aug 31, 2018 at 1:26 PM Phil Edworthy wrote: > The clock for UARTs 0 through 2 is UART012, the clock for UARTs 3 through > 7 is UART34567. > For UART012, we stop the clock driver from changing the clock rate. This > is because the Synopsys UART driver simply sets the reference clock to 16x > the baud rate, but doesn't check if the actual rate is within the required > tolerance. The RZ/N1 clock divider can't provide this (we have to rely on > the UART's internal divider to set the correct clock rate), so you end up > with a clock rate that is way off what you wanted. > > In addition, since the clock is shared between multiple UARTs, you don't > want the driver trying to change the clock rate as it may affect the other > UARTs (which may not have been configured yet, so you don't know what baud > rate they will use). Normally, the clock rate is set early on before Linux > to some very high rate that supports all of the clock rates you want. > > This change stops the UART34567 clock rate from changing for the same > reasons. > > Signed-off-by: Phil Edworthy Reviewed-by: Geert Uytterhoeven i.e. will queue in clk-renesas-for-v4.20. 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