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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 5A46FC433E1 for ; Sat, 6 Jun 2020 20:26:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3735D207DF for ; Sat, 6 Jun 2020 20:26:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="H2EkUw2O" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728910AbgFFU0V (ORCPT ); Sat, 6 Jun 2020 16:26:21 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:57900 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728350AbgFFU0V (ORCPT ); Sat, 6 Jun 2020 16:26:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591475180; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+z9T5HyNDydCcPP8B4mlCiq74wNu8VINCuUykY7+WkQ=; b=H2EkUw2OcqbswVZ3Zr6JIghM7NPwe2s5HqpM2QbgA89TLTqvmB56H+R0xmKTBHnj9wrbR1 XwpOwrcXz1S/pX2Wob5VmC/niMPZTZ49bOz2I9yHWWcK8RF9FG9imKieU4Vzl4HvpVdfb9 KUoucJBeFA9C/vpCVjGb/Aq5k00WSDk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-350-HkaAk3QfPUOMd8HnalNNWg-1; Sat, 06 Jun 2020 16:26:18 -0400 X-MC-Unique: HkaAk3QfPUOMd8HnalNNWg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 96FF5464; Sat, 6 Jun 2020 20:26:16 +0000 (UTC) Received: from x1.localdomain.com (ovpn-112-50.ams2.redhat.com [10.36.112.50]) by smtp.corp.redhat.com (Postfix) with ESMTP id 220365C557; Sat, 6 Jun 2020 20:26:13 +0000 (UTC) From: Hans de Goede To: Thierry Reding , =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= , Jani Nikula , Joonas Lahtinen , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , "Rafael J . Wysocki" , Len Brown Cc: Hans de Goede , linux-pwm@vger.kernel.org, intel-gfx , dri-devel@lists.freedesktop.org, Andy Shevchenko , Mika Westerberg , linux-acpi@vger.kernel.org Subject: [PATCH 04/16] pwm: lpss: Fix off by one error in base_unit math in pwm_lpss_prepare() Date: Sat, 6 Jun 2020 22:25:49 +0200 Message-Id: <20200606202601.48410-5-hdegoede@redhat.com> In-Reply-To: <20200606202601.48410-1-hdegoede@redhat.com> References: <20200606202601.48410-1-hdegoede@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org According to the data-sheet the way the PWM controller works is that each input clock-cycle the base_unit gets added to a N bit counter and that counter overflowing determines the PWM output frequency. So assuming e.g. a 16 bit counter this means that if base_unit is set to 1, after 65535 input clock-cycles the counter has been increased from 0 to 65535 and it will overflow on the next cycle, so it will overflow after every 65536 clock cycles and thus the calculations done in pwm_lpss_prepare() should use 65536 and not 65535. This commit fixes this. Note this also aligns the calculations in pwm_lpss_prepare() with those in pwm_lpss_get_state(). Signed-off-by: Hans de Goede --- drivers/pwm/pwm-lpss.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c index cae74ce61654..a764e062103b 100644 --- a/drivers/pwm/pwm-lpss.c +++ b/drivers/pwm/pwm-lpss.c @@ -93,7 +93,7 @@ static void pwm_lpss_prepare(struct pwm_lpss_chip *lpwm, struct pwm_device *pwm, * The equation is: * base_unit = round(base_unit_range * freq / c) */ - base_unit_range = BIT(lpwm->info->base_unit_bits) - 1; + base_unit_range = BIT(lpwm->info->base_unit_bits); freq *= base_unit_range; base_unit = DIV_ROUND_CLOSEST_ULL(freq, c); @@ -112,7 +112,7 @@ static void pwm_lpss_prepare(struct pwm_lpss_chip *lpwm, struct pwm_device *pwm, orig_ctrl = ctrl = pwm_lpss_read(pwm); ctrl &= ~PWM_ON_TIME_DIV_MASK; - ctrl &= ~(base_unit_range << PWM_BASE_UNIT_SHIFT); + ctrl &= ~((base_unit_range - 1) << PWM_BASE_UNIT_SHIFT); ctrl |= (u32) base_unit << PWM_BASE_UNIT_SHIFT; ctrl |= on_time_div; -- 2.26.2