Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752245Ab3I2KP4 (ORCPT ); Sun, 29 Sep 2013 06:15:56 -0400 Received: from nasmtp01.atmel.com ([192.199.1.245]:42474 "EHLO DVREDG01.corp.atmel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750890Ab3I2KPx (ORCPT ); Sun, 29 Sep 2013 06:15:53 -0400 Message-ID: <5247FCF5.9090501@atmel.com> Date: Sun, 29 Sep 2013 18:12:05 +0800 From: Bo Shen User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130801 Thunderbird/17.0.8 MIME-Version: 1.0 To: Alexandre Belloni CC: Thierry Reding , , Nicolas Ferre , Ludovic Desroches , , Subject: Re: [PATCH] PWM: atmel-pwm: use request/free instead of enable/disable References: <1380312628-6564-1-git-send-email-alexandre.belloni@free-electrons.com> In-Reply-To: <1380312628-6564-1-git-send-email-alexandre.belloni@free-electrons.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.168.5.13] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2662 Lines: 80 Hi Alexandre, On 9/28/2013 04:10, Alexandre Belloni wrote: > I found that disabling a pwm while it is at a low level will actually put it > back at a high level. The main symptom is that leds-pwm is calling pwm_disable() > after setting the duty cycle to 0. Hence, instead of getting a switched off LED, > you get an LED lit up at full brightness. > > Solve that by using the request and free callbacks to enable and disable the > pwm channels and the clock. > > Signed-off-by: Alexandre Belloni > --- > > This patch applies after: > [PATCH v4] PWM: atmel-pwm: add PWM controller driver > > drivers/pwm/pwm-atmel.c | 14 +++++--------- > 1 file changed, 5 insertions(+), 9 deletions(-) > > diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c > index 6af7a50..4526e71 100644 > --- a/drivers/pwm/pwm-atmel.c > +++ b/drivers/pwm/pwm-atmel.c > @@ -209,7 +209,7 @@ static int atmel_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, > return 0; > } > > -static int atmel_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) > +static int atmel_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) > { > struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); > int ret; > @@ -225,23 +225,19 @@ static int atmel_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) > return 0; > } > > -static void atmel_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) > +static void atmel_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) > { > struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); > - u32 val; > > atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm); > - > - val = atmel_pwm_readl(atmel_pwm, PWM_SR); > - if ((val & PWM_SR_ALL_CH_ON) == 0) > - clk_disable(atmel_pwm->clk); > + clk_disable(atmel_pwm->clk); > } > > static const struct pwm_ops atmel_pwm_ops = { > .config = atmel_pwm_config, > .set_polarity = atmel_pwm_set_polarity, > - .enable = atmel_pwm_enable, > - .disable = atmel_pwm_disable, > + .request = atmel_pwm_request, > + .free = atmel_pwm_free, This will cause pwmadd_chip failure. Code from , in function: pwmadd_chip() ---8>--- if (!chip || !chip->dev || !chip->ops || !chip->ops->config || !chip->ops->enable || !chip->ops->disable) return -EINVAL; ---<8--- > .owner = THIS_MODULE, > }; > Best Regards, Bo Shen -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/