From patchwork Wed Jul 8 21:14:19 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Hans de Goede X-Patchwork-Id: 11652559 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 24226913 for ; Wed, 8 Jul 2020 21:15:02 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 F0736206E9 for ; Wed, 8 Jul 2020 21:15:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ZIJZl4bh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F0736206E9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 74AC26E40F; Wed, 8 Jul 2020 21:14:53 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from us-smtp-delivery-1.mimecast.com (us-smtp-1.mimecast.com [205.139.110.61]) by gabe.freedesktop.org (Postfix) with ESMTPS id 640176E40F for ; Wed, 8 Jul 2020 21:14:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1594242891; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vZtt75CEcTdNAp9GFIY6y7MMo5rkA/s2Do7t8OqOgL8=; b=ZIJZl4bh6jibempmfnwHXH5/PZryNJi0DxVQ+yRFLtUXlqmEy5rnjR1NjYt9xaP0bt1+5d hM17eFPq1mOevk40qqZeuYYeNQUZWqCA1GbQsnZilUHqZTUv/bsYR+6ISt5ivljltLh6Vt Ym0LY9UvdIYCcx35RupJDujesFadcAY= 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-474-hw8LPw14Ori1CRNoAqEh5Q-1; Wed, 08 Jul 2020 17:14:47 -0400 X-MC-Unique: hw8LPw14Ori1CRNoAqEh5Q-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 362A8E91A; Wed, 8 Jul 2020 21:14:45 +0000 (UTC) Received: from x1.localdomain.com (ovpn-112-5.ams2.redhat.com [10.36.112.5]) by smtp.corp.redhat.com (Postfix) with ESMTP id AA1BB79220; Wed, 8 Jul 2020 21:14:42 +0000 (UTC) From: Hans de Goede To: Thierry Reding , =?utf-8?q?Uwe_Kleine-K=C3=B6n?= =?utf-8?q?ig?= , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , =?utf-8?b?VmlsbGUgU3lyasOkbMOk?= , "Rafael J . Wysocki" , Len Brown Subject: [PATCH v4 03/16] pwm: lpss: Fix off by one error in base_unit math in pwm_lpss_prepare() Date: Wed, 8 Jul 2020 23:14:19 +0200 Message-Id: <20200708211432.28612-4-hdegoede@redhat.com> In-Reply-To: <20200708211432.28612-1-hdegoede@redhat.com> References: <20200708211432.28612-1-hdegoede@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-pwm@vger.kernel.org, linux-acpi@vger.kernel.org, intel-gfx , dri-devel@lists.freedesktop.org, Hans de Goede , Andy Shevchenko , Mika Westerberg Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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(). Note this effectively reverts commit 684309e5043e ("pwm: lpss: Avoid potential overflow of base_unit"). The next patch in this series really fixes the potential overflow of the base_unit value. Fixes: 684309e5043e ("pwm: lpss: Avoid potential overflow of base_unit") Reviewed-by: Andy Shevchenko Acked-by: Uwe Kleine-König Signed-off-by: Hans de Goede --- Changes in v3: - Add Fixes tag - Add Reviewed-by: Andy Shevchenko tag --- drivers/pwm/pwm-lpss.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c index 9d965ffe66d1..43b1fc634af1 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); @@ -104,8 +104,8 @@ 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); - base_unit &= base_unit_range; + ctrl &= ~((base_unit_range - 1) << PWM_BASE_UNIT_SHIFT); + base_unit &= (base_unit_range - 1); ctrl |= (u32) base_unit << PWM_BASE_UNIT_SHIFT; ctrl |= on_time_div;