linux-kernel - [PATCH] pwm: lpc32xx

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Message-Id: <1352375184-4920-1-git-send-email-alban.bedel@avionic-design.de>
Date:	Thu,  8 Nov 2012 12:46:24 +0100
From:	Alban Bedel <alban.bedel@...onic-design.de>
To:	Roland Stigge <stigge@...com.de>
Cc:	Thierry Reding <thierry.reding@...onic-design.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Alexandre Pereira da Silva <aletes.xgr@...il.com>,
	Alban Bedel <alban.bedel@...onic-design.de>
Subject: [PATCH] pwm: lpc32xx - Fix the PWM polarity

The duty cycles value goes from 1 (99% HIGH) to 256 (0% HIGH) but it
is stored modulo 256 in the register as it is only 8 bits wide.

Signed-off-by: Alban Bedel <alban.bedel@...onic-design.de>
---
 drivers/pwm/pwm-lpc32xx.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/pwm/pwm-lpc32xx.c b/drivers/pwm/pwm-lpc32xx.c
index adb87f0..2590f8d 100644
--- a/drivers/pwm/pwm-lpc32xx.c
+++ b/drivers/pwm/pwm-lpc32xx.c
@@ -51,7 +51,9 @@ static int lpc32xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	c = 256 * duty_ns;
 	do_div(c, period_ns);
-	duty_cycles = c;
+	if (c > 255)
+		c = 255;
+	duty_cycles = 256 - c;
 
 	writel(PWM_ENABLE | PWM_RELOADV(period_cycles) | PWM_DUTY(duty_cycles),
 		lpc32xx->base + (pwm->hwpwm << 2));
-- 
1.7.0.4

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