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=-5.5 required=3.0 tests=DKIM_ADSP_ALL,DKIM_INVALID, DKIM_SIGNED,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 6BE99C4CECE for ; Mon, 14 Oct 2019 13:53:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 408CE2133F for ; Mon, 14 Oct 2019 13:53:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=megous.com header.i=@megous.com header.b="qeaJSpN7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732364AbfJNNxP (ORCPT ); Mon, 14 Oct 2019 09:53:15 -0400 Received: from vps.xff.cz ([195.181.215.36]:39696 "EHLO vps.xff.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731092AbfJNNxO (ORCPT ); Mon, 14 Oct 2019 09:53:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=megous.com; s=mail; t=1571061192; bh=46QzCIBZ/9atA9i8sP3TsXg10uJJ6p13+mX/uBQH05Y=; h=From:To:Cc:Subject:Date:From; b=qeaJSpN7BUJp2ZteQ5BjyIkVRC6U0UOhE7/gTCpY+DprLpl8kJMvhno9FN5fEXAj/ vqfuwWbW7gK6ALcnPDN5dGh0qLtwAAR92w1PbxUXFpnTl3wx9TeUVdsvoQiTHkucCk 6LgmSYX/mtr2I/n5v+Sbbo87xQkbzlHzWd6xUGPY= From: megous@megous.com Cc: Ondrej Jirman , Thierry Reding , =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= , Maxime Ripard , Chen-Yu Tsai , linux-pwm@vger.kernel.org (open list:PWM SUBSYSTEM), linux-arm-kernel@lists.infradead.org (moderated list:ARM/Allwinner sunXi SoC support), linux-kernel@vger.kernel.org (open list) Subject: [PATCH] pwm: sun4i: Fix incorrect calculation of duty_cycle/period Date: Mon, 14 Oct 2019 15:53:03 +0200 Message-Id: <20191014135303.2944058-1-megous@megous.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ondrej Jirman Since 5.4-rc1, pwm_apply_state calls ->get_state after ->apply if available, and this revealed an issue with integer precision when calculating duty_cycle and period for the currently set state in ->get_state callback. This issue manifested in broken backlight on several Allwinner based devices. Previously this worked, because ->apply updated the passed state directly. Fixes: deb9c462f4e53 ("pwm: sun4i: Don't update the state for the caller of pwm_apply_state") Signed-off-by: Ondrej Jirman --- drivers/pwm/pwm-sun4i.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c index 6f5840a1a82d..05273725a9ff 100644 --- a/drivers/pwm/pwm-sun4i.c +++ b/drivers/pwm/pwm-sun4i.c @@ -137,10 +137,10 @@ static void sun4i_pwm_get_state(struct pwm_chip *chip, val = sun4i_pwm_readl(sun4i_pwm, PWM_CH_PRD(pwm->hwpwm)); - tmp = prescaler * NSEC_PER_SEC * PWM_REG_DTY(val); + tmp = (u64)prescaler * NSEC_PER_SEC * PWM_REG_DTY(val); state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate); - tmp = prescaler * NSEC_PER_SEC * PWM_REG_PRD(val); + tmp = (u64)prescaler * NSEC_PER_SEC * PWM_REG_PRD(val); state->period = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate); } -- 2.23.0