From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755705AbaCNOT5 (ORCPT ); Fri, 14 Mar 2014 10:19:57 -0400 Received: from top.free-electrons.com ([176.31.233.9]:48116 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754798AbaCNOTU (ORCPT ); Fri, 14 Mar 2014 10:19:20 -0400 From: Alexandre Belloni To: Thierry Reding Cc: linux-kernel@vger.kernel.org, Nicolas Ferre , Bo Shen , linux-pwm@vger.kernel.org, Alexandre Belloni Subject: [PATCH 2/2] PWM: atmel: correct CDTY calculation Date: Fri, 14 Mar 2014 15:19:09 +0100 Message-Id: <1394806749-29778-3-git-send-email-alexandre.belloni@free-electrons.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1394806749-29778-1-git-send-email-alexandre.belloni@free-electrons.com> References: <1394806749-29778-1-git-send-email-alexandre.belloni@free-electrons.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>From the datasheet, the actual duty cycle is: (period - (1/clk) * CDTY)/period This actually correct the polarity of the PWM and solves the issue that pwm-leds exhibits: when setting a duty cycle of 0 and then disabling a channel, the level was wrong (1 when the polarity was normal and 0 when the polarity was inversed). Signed-off-by: Alexandre Belloni --- drivers/pwm/pwm-atmel.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c index 2d69e9c431dd..0adc952cc4ef 100644 --- a/drivers/pwm/pwm-atmel.c +++ b/drivers/pwm/pwm-atmel.c @@ -133,7 +133,7 @@ static int atmel_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, prd = div; div *= duty_ns; do_div(div, period_ns); - dty = div; + dty = prd - div; ret = clk_enable(atmel_pwm->clk); if (ret) { -- 1.8.3.2