From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: From: ryang To: Peter De Schrijver Cc: Prashant Gaikwad , Michael Turquette , Stephen Boyd , Thierry Reding , Jonathan Hunter , linux-clk@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, ryang Subject: [PATCH] clk: tegra: Fix an infinite loop when clock rate is zero Date: Fri, 21 Sep 2018 18:00:37 -0400 Message-Id: <20180921220037.16862-1-decatf@gmail.com> List-ID: Calling clk_set_rate or clk_round_rate will lock up the kernel when the rate is zero. This avoids the infinite loop and uses a slightly more optimized p divider calculation. Signed-off-by: ryang --- drivers/clk/tegra/clk-pll.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/clk/tegra/clk-pll.c b/drivers/clk/tegra/clk-pll.c index 830d1c87fa7c..17a058c3bbc1 100644 --- a/drivers/clk/tegra/clk-pll.c +++ b/drivers/clk/tegra/clk-pll.c @@ -582,9 +582,8 @@ static int _calc_rate(struct clk_hw *hw, struct tegra_clk_pll_freq_table *cfg, } /* Raise VCO to guarantee 0.5% accuracy */ - for (cfg->output_rate = rate; cfg->output_rate < 200 * cfreq; - cfg->output_rate <<= 1) - p_div++; + p_div = rate ? fls((200 * cfreq) / rate) : 0; + cfg->output_rate = rate << p_div; cfg->m = parent_rate / cfreq; cfg->n = cfg->output_rate / cfreq; -- 2.17.1 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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 E6154ECE560 for ; Fri, 21 Sep 2018 22:00:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 82DC72156B for ; Fri, 21 Sep 2018 22:00:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="A85+X/Lj" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 82DC72156B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-clk-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391413AbeIVDvg (ORCPT ); Fri, 21 Sep 2018 23:51:36 -0400 Received: from mail-io1-f68.google.com ([209.85.166.68]:37030 "EHLO mail-io1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391323AbeIVDvg (ORCPT ); Fri, 21 Sep 2018 23:51:36 -0400 Received: by mail-io1-f68.google.com with SMTP id v14-v6so13571189iob.4; Fri, 21 Sep 2018 15:00:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=DX9KFFcKuSzYEGeCtNdPuIjmyHcNuxj4/0N5ygp7TZw=; b=A85+X/LjIG+tZkH4M0GMnw/q34INpo5VbpvB8/7jte3R8/c7jxRgAgZfeP/SHvtW1y YYYnZcnK+h+PngUryKjcQHEjTeCi3Ski6sdTxN1+xMSX0HNfBDmraV5KOL1SI9q1oXCL jQUfN20xOb5H8bDTF12PMd4fwOswA33EXNfjulG1okMM8vc5Htp/Ua9v4CTmyGdsgPsL M+SKV2HzwpGBH4uPAd2n9ANA9aTgeAINORC87hdtUtTRwJZ67eglizAXb5LSrqTBQamL L10fpHJNiUqekWN6CwGXkHOTVGLO/3CE5csUmoFZNglKm8lIpg1IFQnr8RyhY2yHe7s9 WmSw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=DX9KFFcKuSzYEGeCtNdPuIjmyHcNuxj4/0N5ygp7TZw=; b=awljl6x9M0SICga3SlWFiaYpLEINhwEIyp1tgwGpAw/RPu8mfDiLGDXgJw+v6O+QkE UivmSeDbtjJP5pK5oRH3HjRZz5XwrAbUjs/+Rf3kHDFspaIBsb1PwhLWG4oSlFouzaf8 JsCtGAVMl+3OUlJ8ocSFN+UjRCYYdEZ6+iJCiqAB3gl+j37cwLD/oesTeu6J2gPNN8rD 8WCvl26IdhgeKQnulyN8adfJ+lg465phkymt/6WaFqijP/wpV0QsQyqodzR5Tpg4WWK6 Ruz9M6uD0p86xc+Mv6kZBwY6K8mb/Oh7JpQjUpHKhBkTAeSr3l+PUxkiFVk6/g6Wfz8q 7b3g== X-Gm-Message-State: ABuFfoi+q9UG/6rL1w50G4Y1TBsbcHV3NurrRHCyePfWm7wp3cbw51UZ +3VxYwS/0cRvATNwFMNWOw== X-Google-Smtp-Source: ACcGV60wuW+FmubhL3A3cieTqa8DbO1vWAY2LUns9lqZaKn9IQWq0xV7TuOh1ezEGATeMawq7iDvNA== X-Received: by 2002:a5e:c009:: with SMTP id u9-v6mr7327914iol.155.1537567247949; Fri, 21 Sep 2018 15:00:47 -0700 (PDT) Received: from localhost.localdomain (CPE1cabc0918a93-CM1cabc0918a90.cpe.net.cable.rogers.com. [99.229.26.117]) by smtp.gmail.com with ESMTPSA id n194-v6sm2478859itg.14.2018.09.21.15.00.46 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 21 Sep 2018 15:00:47 -0700 (PDT) From: ryang To: Peter De Schrijver Cc: Prashant Gaikwad , Michael Turquette , Stephen Boyd , Thierry Reding , Jonathan Hunter , linux-clk@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, ryang Subject: [PATCH] clk: tegra: Fix an infinite loop when clock rate is zero Date: Fri, 21 Sep 2018 18:00:37 -0400 Message-Id: <20180921220037.16862-1-decatf@gmail.com> X-Mailer: git-send-email 2.17.1 Sender: linux-clk-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org Message-ID: <20180921220037.YsZ7a2mVon1DhWAWNgQb9HzyzCeoZImq6QNQRFlL9hI@z> Calling clk_set_rate or clk_round_rate will lock up the kernel when the rate is zero. This avoids the infinite loop and uses a slightly more optimized p divider calculation. Signed-off-by: ryang --- drivers/clk/tegra/clk-pll.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/clk/tegra/clk-pll.c b/drivers/clk/tegra/clk-pll.c index 830d1c87fa7c..17a058c3bbc1 100644 --- a/drivers/clk/tegra/clk-pll.c +++ b/drivers/clk/tegra/clk-pll.c @@ -582,9 +582,8 @@ static int _calc_rate(struct clk_hw *hw, struct tegra_clk_pll_freq_table *cfg, } /* Raise VCO to guarantee 0.5% accuracy */ - for (cfg->output_rate = rate; cfg->output_rate < 200 * cfreq; - cfg->output_rate <<= 1) - p_div++; + p_div = rate ? fls((200 * cfreq) / rate) : 0; + cfg->output_rate = rate << p_div; cfg->m = parent_rate / cfreq; cfg->n = cfg->output_rate / cfreq; -- 2.17.1