From: Jason Chen <jason.chen@linaro.org>
Date: Mon, 19 Dec 2011 03:23:28 +0000 (+0800)
Subject: ARM:imx:fix pwm period value
X-Git-Tag: firefly_0821_release~7541^2~2055
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=8048ac75378918eab0f68ba175915e72ef73e0da;p=firefly-linux-kernel-4.4.55.git

ARM:imx:fix pwm period value

commit 5776ac2eb33164c77cdb4d2b48feee15616eaba3 upstream.

According to imx pwm RM, the real period value should be
PERIOD value in PWMPR plus 2.

PWMO (Hz) = PCLK(Hz) / (period +2)

Signed-off-by: Jason Chen <jason.chen@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/arch/arm/plat-mxc/pwm.c b/arch/arm/plat-mxc/pwm.c
index 7bf2a00034f8..f4b68beddbb3 100644
--- a/arch/arm/plat-mxc/pwm.c
+++ b/arch/arm/plat-mxc/pwm.c
@@ -77,6 +77,15 @@ int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
 		do_div(c, period_ns);
 		duty_cycles = c;
 
+		/*
+		 * according to imx pwm RM, the real period value should be
+		 * PERIOD value in PWMPR plus 2.
+		 */
+		if (period_cycles > 2)
+			period_cycles -= 2;
+		else
+			period_cycles = 0;
+
 		writel(duty_cycles, pwm->mmio_base + MX3_PWMSAR);
 		writel(period_cycles, pwm->mmio_base + MX3_PWMPR);