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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 0482DC73C53 for ; Tue, 9 Jul 2019 20:21:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C838F214AF for ; Tue, 9 Jul 2019 20:21:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="APoJ6iLS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729526AbfGIUVP (ORCPT ); Tue, 9 Jul 2019 16:21:15 -0400 Received: from mail-pg1-f193.google.com ([209.85.215.193]:37947 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727241AbfGIUVP (ORCPT ); Tue, 9 Jul 2019 16:21:15 -0400 Received: by mail-pg1-f193.google.com with SMTP id z75so9218pgz.5 for ; Tue, 09 Jul 2019 13:21:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=RU2m3gdZjiC+rwxYFcfrlXuCSiHOAqLHTQmxdQ6quvM=; b=APoJ6iLSb9+I/dFVYqPsmB2MKY8b9MOwQVQPfZ95RwL+DcRc9ZF/tr7/xjRnmlKlQq tNczBH3MfkCVOP6gv2fUmWqxsETPGbFBTk6WYxwKSia4ASivhmPeWmt0FNVU6ijG+R0q LiHb9J7/QNQkeJht8yH79vLJrPI18mxC10fH8yq71FuY+GQ7B+SuajLrdfSEcO4rdFd+ 1RaZRcQ90wXTSCURHbLT0uk4U/ri22i3kEf69klAn46/gc26CKFsWoegQJmKmBSTeUv3 AuR70i6IkB+fENHBN1oIVUdHacxE6LP2v4JTspCT6TedbgCobzLCRw/fwjwOM/xNeEO+ g9qg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=RU2m3gdZjiC+rwxYFcfrlXuCSiHOAqLHTQmxdQ6quvM=; b=lSSEF/w8NekevBS1QbNr67fwo5LzN2mbg4KxyUDG516DgmKV5E3S4M1mHo6C6W8NPa g/uelJq7qx9ZHkF3lP42qp8LVk/AliFB9fjVN5OJNO0JWgktxxnNlgildraei/8q1wjz /fi+jGybgNYqAhhBs5Y8/aGfNnTAMJA/BD+dFk8Q+fzFIw+GHpHANdDN9iorWZMfotBA nZTNA29bWcXHISB1ZUj/KFSomdGjumiSDwm8S+rYS+1e9k384mXt1C1jzP/tdgELzUoh DfbJw22eDTwNAyrGn1WKoJxfnvStQEFYl9pPAd2HliUEmxR/SKMXcQh5DndpLHC+q2lv EQyQ== X-Gm-Message-State: APjAAAVJrnEsAwYRTRnhQkriWc1r0ld52T5CPCjWPg97SI0IcXxZ8mmz qdHrlcYsALIiiAij1oNTXsCkg20z X-Google-Smtp-Source: APXvYqweCx+mfF993hFR/ndG1uW/vnp2lXbLEgCta67tGh9YVEyNYWTwdmPo8Y8bKmfMni8nb+8Dtg== X-Received: by 2002:a63:6103:: with SMTP id v3mr33936998pgb.161.1562703674647; Tue, 09 Jul 2019 13:21:14 -0700 (PDT) Received: from localhost ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id k16sm21298657pfa.87.2019.07.09.13.21.13 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 09 Jul 2019 13:21:14 -0700 (PDT) Date: Tue, 9 Jul 2019 13:21:13 -0700 From: Guenter Roeck To: Melin Tomas Cc: "wim@linux-watchdog.org" , "linux-watchdog@vger.kernel.org" Subject: Re: [PATCH v3 4/4] watchdog: cadence_wdt: Support all available prescaler values Message-ID: <20190709202113.GD27937@roeck-us.net> References: <20190709200801.42313-1-tomas.melin@vaisala.com> <20190709200801.42313-5-tomas.melin@vaisala.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190709200801.42313-5-tomas.melin@vaisala.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-watchdog-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org On Tue, Jul 09, 2019 at 08:09:06PM +0000, Melin Tomas wrote: > Cadence watchdog HW supports prescaler values of > 8, 64, 512 and 4096. > > Add support to select prescaler values of 8 and 64 for lower > input clock frequencies. > > Prescaler value is selected to keep timeout resolution of 1 second. > For clock frequencies below 32kHz, 1 second resolution does > no longer hold, thereby returning an error. > I think I am missing something. Why was this valid/supported up to now, and if it was, why is it no longer possible to support it ? I am also a bit confused about the logic. With a slower clock, I would expect that the timeouts are getting larger, not smaller. Can you explain ? > Signed-off-by: Tomas Melin > --- > drivers/watchdog/cadence_wdt.c | 21 +++++++++++++++------ > 1 file changed, 15 insertions(+), 6 deletions(-) > > diff --git a/drivers/watchdog/cadence_wdt.c b/drivers/watchdog/cadence_wdt.c > index 0bdb275d904a..037faf557f9d 100644 > --- a/drivers/watchdog/cadence_wdt.c > +++ b/drivers/watchdog/cadence_wdt.c > @@ -33,16 +33,17 @@ > #define CDNS_WDT_COUNTER_VALUE_DIVISOR 0x1000 > > /* Clock prescaler value and selection */ > +#define CDNS_WDT_PRESCALE_8 8 > #define CDNS_WDT_PRESCALE_64 64 > #define CDNS_WDT_PRESCALE_512 512 > #define CDNS_WDT_PRESCALE_4096 4096 > +#define CDNS_WDT_PRESCALE_SELECT_8 0 > #define CDNS_WDT_PRESCALE_SELECT_64 1 > #define CDNS_WDT_PRESCALE_SELECT_512 2 > #define CDNS_WDT_PRESCALE_SELECT_4096 3 > > -/* Input clock frequency */ > -#define CDNS_WDT_CLK_10MHZ 10000000 > -#define CDNS_WDT_CLK_75MHZ 75000000 > +/* Base input clock frequency */ > +#define CDNS_WDT_CLK_32KHZ 32768 ^ Please use a tab here > > /* Counter maximum value */ > #define CDNS_WDT_COUNTER_MAX 0xFFF > @@ -318,10 +319,18 @@ static int cdns_wdt_probe(struct platform_device *pdev) > return ret; > > clock_f = clk_get_rate(wdt->clk); > - if (clock_f == 0) { > - dev_err(dev, "invalid clock frequency, (f=%lu)\n", clock_f); > + if (clock_f < CDNS_WDT_CLK_32KHZ) { > + dev_err(dev, > + "cannot find suitable clock prescaler, (f=%lu)\n", > + clock_f); > return -EINVAL; > - } else if (clock_f <= CDNS_WDT_CLK_75MHZ) { > + } else if (clock_f <= CDNS_WDT_CLK_32KHZ * CDNS_WDT_PRESCALE_8) { > + wdt->prescaler = CDNS_WDT_PRESCALE_8; > + wdt->ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_8; > + } else if (clock_f <= CDNS_WDT_CLK_32KHZ * CDNS_WDT_PRESCALE_64) { > + wdt->prescaler = CDNS_WDT_PRESCALE_64; > + wdt->ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_64; > + } else if (clock_f <= CDNS_WDT_CLK_32KHZ * CDNS_WDT_PRESCALE_512) { > wdt->prescaler = CDNS_WDT_PRESCALE_512; > wdt->ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_512; > } else { > -- > 2.17.2 >