From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755586AbaCNOTW (ORCPT ); Fri, 14 Mar 2014 10:19:22 -0400 Received: from top.free-electrons.com ([176.31.233.9]:48114 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755560AbaCNOTS (ORCPT ); Fri, 14 Mar 2014 10:19:18 -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 1/2] PWM: atmel: Fix polarity handling Date: Fri, 14 Mar 2014 15:19:08 +0100 Message-Id: <1394806749-29778-2-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 When atmel_pwm_config() calculates and then sets the prescaler, it is overwriting the channel's CMR register so we are losing the CPOL configuration. As atmel_pwm_config() is always called before enabling a channel, inverting the polarity doesn't work. Fix that by reading CMR first and only overwriting the prescaler bits. Signed-off-by: Alexandre Belloni --- drivers/pwm/pwm-atmel.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c index bf4144a14661..2d69e9c431dd 100644 --- a/drivers/pwm/pwm-atmel.c +++ b/drivers/pwm/pwm-atmel.c @@ -32,6 +32,7 @@ /* Bit field in CMR */ #define PWM_CMR_CPOL (1 << 9) #define PWM_CMR_UPD_CDTY (1 << 10) +#define PWM_CMR_CPRE_MSK 0xF /* The following registers for PWM v1 */ #define PWMV1_CDTY 0x04 @@ -104,6 +105,7 @@ static int atmel_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, unsigned long clk_rate, prd, dty; unsigned long long div; unsigned int pres = 0; + u32 val; int ret; if (test_bit(PWMF_ENABLED, &pwm->flags) && (period_ns != pwm->period)) { @@ -139,7 +141,10 @@ static int atmel_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, return ret; } - atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, pres); + /* It is necessary to preserve CPOL, inside CMR */ + val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR); + val = (val & ~PWM_CMR_CPRE_MSK) | (pres & PWM_CMR_CPRE_MSK); + atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val); atmel_pwm->config(chip, pwm, dty, prd); clk_disable(atmel_pwm->clk); -- 1.8.3.2