linux-kernel - [PATCH 1/1] Atmel-PWM: Fixed the PWM channel enable/disable issue which will cause the PWM output stop working after reenable. THe PWM channel status register is read to ensure the PWM channel is really enabled or disabled.

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Date:	Wed,  1 Oct 2014 15:08:30 -0600
From:	robert yang <hachyang@...il.com>
To:	Thierry Reding <thierry.reding@...il.com>,
	linux-pwm@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, ryang <ryang@...h.com>
Subject: [PATCH 1/1] Atmel-PWM: Fixed the PWM channel enable/disable issue which will cause the PWM output stop working after reenable. THe PWM channel status register is read to ensure  the PWM channel is really enabled or disabled.

From: ryang <ryang@...h.com>

Signed-off-by: ryang <ryang@...h.com>
---
 drivers/pwm/pwm-atmel.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c
index 6e700a5..bab933a 100644
--- a/drivers/pwm/pwm-atmel.c
+++ b/drivers/pwm/pwm-atmel.c
@@ -237,7 +237,10 @@ static int atmel_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 	}
 
 	atmel_pwm_writel(atmel_pwm, PWM_ENA, 1 << pwm->hwpwm);
-
+	while (!(atmel_pwm_readl(atmel_pwm, PWM_SR) & (1 << pwm->hwpwm))) {
+		atmel_pwm_writel(atmel_pwm, PWM_ENA, 1 << pwm->hwpwm);
+		cpu_relax();
+	}
 	return 0;
 }
 
@@ -246,7 +249,10 @@ static void atmel_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
 
 	atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm);
-
+	while (atmel_pwm_readl(atmel_pwm, PWM_SR) & (1 << pwm->hwpwm)) {
+		atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm);
+		cpu_relax();
+	}
 	clk_disable(atmel_pwm->clk);
 }
 
-- 
1.9.1

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