From patchwork Wed Jan 20 16:16:25 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Baruch Siach X-Patchwork-Id: 1429311 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-pwm-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4DLW2Z1SKMz9sVX for ; Thu, 21 Jan 2021 03:20:06 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403808AbhATQTc (ORCPT ); Wed, 20 Jan 2021 11:19:32 -0500 Received: from guitar.tcltek.co.il ([192.115.133.116]:55083 "EHLO mx.tkos.co.il" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391354AbhATQR3 (ORCPT ); Wed, 20 Jan 2021 11:17:29 -0500 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 545E744079E; Wed, 20 Jan 2021 18:16:38 +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 Cc: Baruch Siach , Andrew Lunn , Gregory Clement , Russell King , Sebastian Hesselbarth , Thomas Petazzoni , Chris Packham , Sascha Hauer , Ralph Sennhauser , linux-pwm@vger.kernel.org, linux-gpio@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH v5 1/4] gpio: mvebu: improve pwm period calculation accuracy Date: Wed, 20 Jan 2021 18:16:25 +0200 Message-Id: <0c70e683121eb6970cfce31aa105cd09d52297e6.1611128398.git.baruch@tkos.co.il> X-Mailer: git-send-email 2.29.2 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org Change 'off' register value calculation from $off = (period - duty_cycle) * clkrate / NSEC_PER_SEC to $off = (period * clkrate / NSEC_PER_SEC) - $on That is, divide the full period value to reduce rounding error. Reported-by: Uwe Kleine-König Reviewed-by: Uwe Kleine-König Reviewed-by: Linus Walleij Signed-off-by: Baruch Siach --- drivers/gpio/gpio-mvebu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c index a912a8fed197..c424d88e9e2b 100644 --- a/drivers/gpio/gpio-mvebu.c +++ b/drivers/gpio/gpio-mvebu.c @@ -715,9 +715,9 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, else on = 1; - val = (unsigned long long) mvpwm->clk_rate * - (state->period - state->duty_cycle); + val = (unsigned long long) mvpwm->clk_rate * state->period; do_div(val, NSEC_PER_SEC); + val -= on; if (val > UINT_MAX) return -EINVAL; if (val)