From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753024AbdCMJVy (ORCPT ); Mon, 13 Mar 2017 05:21:54 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:39532 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751842AbdCMIkd (ORCPT ); Mon, 13 Mar 2017 04:40:33 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Clemens Gruber , Mika Westerberg , Thierry Reding Subject: [PATCH 4.4 22/36] pwm: pca9685: Fix period change with same duty cycle Date: Mon, 13 Mar 2017 16:39:22 +0800 Message-Id: <20170313083353.860036978@linuxfoundation.org> X-Mailer: git-send-email 2.12.0 In-Reply-To: <20170313083352.550085638@linuxfoundation.org> References: <20170313083352.550085638@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Clemens Gruber commit 8d254a340efb12b40c4c1ff25a48a4f48f7bbd6b upstream. When first implementing support for changing the output frequency, an optimization was added to continue the PWM after changing the prescaler without having to reprogram the ON and OFF registers for the duty cycle, in case the duty cycle stayed the same. This was flawed, because we compared the absolute value of the duty cycle in nanoseconds instead of the ratio to the period. Fix the problem by removing the shortcut. Fixes: 01ec8472009c9 ("pwm-pca9685: Support changing the output frequency") Signed-off-by: Clemens Gruber Reviewed-by: Mika Westerberg Signed-off-by: Thierry Reding Signed-off-by: Greg Kroah-Hartman --- drivers/pwm/pwm-pca9685.c | 11 ----------- 1 file changed, 11 deletions(-) --- a/drivers/pwm/pwm-pca9685.c +++ b/drivers/pwm/pwm-pca9685.c @@ -65,7 +65,6 @@ #define PCA9685_MAXCHAN 0x10 #define LED_FULL (1 << 4) -#define MODE1_RESTART (1 << 7) #define MODE1_SLEEP (1 << 4) #define MODE2_INVRT (1 << 4) #define MODE2_OUTDRV (1 << 2) @@ -117,16 +116,6 @@ static int pca9685_pwm_config(struct pwm udelay(500); pca->period_ns = period_ns; - - /* - * If the duty cycle did not change, restart PWM with - * the same duty cycle to period ratio and return. - */ - if (duty_ns == pca->duty_ns) { - regmap_update_bits(pca->regmap, PCA9685_MODE1, - MODE1_RESTART, 0x1); - return 0; - } } else { dev_err(chip->dev, "prescaler not set: period out of bounds!\n");