From patchwork Wed Jan 13 09:22:45 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Baruch Siach X-Patchwork-Id: 12016227 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=-17.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 64F92C433E0 for ; Wed, 13 Jan 2021 09:25:46 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E0F532339D for ; Wed, 13 Jan 2021 09:25:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E0F532339D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=tkos.co.il Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=e62MZjARyPEQW5eADSYf53R8lUETSevkcLPpbbkCxs4=; b=yDhGJ4PWksDCJwcXWFywz0oxZ 7QLzelc/eOzzj+ghShL8Z7MVoFjuiTs640YcEMzARNfcA+WWO9IS81ZI78KFBIC9zNhm9XVkTPslI iQ1faMFjj0G8DEI1tZIYGtl13O79VMhmZOtmwtLuImMmk8ezPKMOEkK9mxim5uKGHOCX6h3t51eGy dR4gFvnYS3Uw1dnBQKF/23P0Po3jiG4YZvYpqLRqTWWRF44eLD4VbLbESpXhgZwKw+3rJQoeAt9HO Tco1urJe49S0OO0UYS8uIoZ2pt9w0DlLlIrvfgQ/OXrecAei3LeatZnK3nf4p2FPDVZ+cJR/99lxC aM5W137qw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kzcNn-0000pn-Nd; Wed, 13 Jan 2021 09:24:03 +0000 Received: from guitar.tcltek.co.il ([192.115.133.116] helo=mx.tkos.co.il) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kzcNG-0000YG-Ke for linux-arm-kernel@lists.infradead.org; Wed, 13 Jan 2021 09:23:32 +0000 Received: from tarshish.tkos.co.il (unknown [10.0.8.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mx.tkos.co.il (Postfix) with ESMTPS id 5F0DD4407B2; Wed, 13 Jan 2021 11:23:28 +0200 (IST) From: Baruch Siach To: Thierry Reding , =?utf-8?q?Uwe_Kleine-K=C3=B6n?= =?utf-8?q?ig?= , Lee Jones , Linus Walleij , Bartosz Golaszewski Subject: [PATCH v2 5/5] gpio: mvebu: document zero pwm duty cycle limitation Date: Wed, 13 Jan 2021 11:22:45 +0200 Message-Id: <08fb30de22864ecfecf6f9bc59ca78a61a34b3fd.1610529002.git.baruch@tkos.co.il> X-Mailer: git-send-email 2.29.2 In-Reply-To: References: MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210113_042331_043767_BA994D6B X-CRM114-Status: GOOD ( 16.64 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Andrew Lunn , Baruch Siach , linux-pwm@vger.kernel.org, Gregory Clement , Russell King , linux-gpio@vger.kernel.org, Chris Packham , Thomas Petazzoni , Ralph Sennhauser , Sascha Hauer , linux-arm-kernel@lists.infradead.org, Sebastian Hesselbarth Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Add a comment on why the code never sets on/off registers to zero. Reported-by: Uwe Kleine-König Analyzed-by: Russell King Signed-off-by: Baruch Siach --- drivers/gpio/gpio-mvebu.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c index 6b017854ce61..09780944bef9 100644 --- a/drivers/gpio/gpio-mvebu.c +++ b/drivers/gpio/gpio-mvebu.c @@ -706,6 +706,10 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, do_div(val, NSEC_PER_SEC); if (val > UINT_MAX) return -EINVAL; + /* + * Zero on/off values don't work as expected. Experimentation shows + * that zero value is treated as 2^32. This behavior is not documented. + */ if (val) on = val; else