| Date | Tue, 03 Jan 2012 14:33:14 -0800 | From | Greg KH <> | Subject | [41/75] ARM:imx:fix pwm period value |
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3.1-stable review patch. If anyone has any objections, please let me know.
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From: Jason Chen <jason.chen@linaro.org>
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>
--- arch/arm/plat-mxc/pwm.c | 9 +++++++++ 1 file changed, 9 insertions(+)
--- 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, i 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);
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