ENGR00219856-2 mxc pwm: do pwm software reset after disable

When android doing suspend/resume, we may meet the issue of
backlight is not on (pwm pin no signal) after system wakeup.
The root cause is PWM sample can not be set into the PWMSAR
register after pwm being used and disabled for a while.
The value read back after write is 0 when this issue happens.

Do a software reset after pwm disable can resolve this
issue, this makes sure the next sample update is correct.
Signed-off-by: Xinyu Chen <xinyu.chen@freescale.com>

arch/arm/plat-mxc/pwm.c

@@ -6,7 +6,7 @@
  * published by the Free Software Foundation.
  *
  * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
- * Copyright 2009-2011 Freescale Semiconductor, Inc. All Rights Reserved.
+ * Copyright 2009-2012 Freescale Semiconductor, Inc. All Rights Reserved.
  */
 
 #include <linux/module.h>
@@ -39,6 +39,7 @@
 #define MX3_PWMCR_DBGEN			(1 << 22)
 #define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16)
 #define MX3_PWMCR_CLKSRC_IPG      (1 << 16)
+#define MX3_PWMCR_SWR             (1 << 3)
 #define MX3_PWMCR_EN              (1 << 0)
 
 #define MX3_PWMCR_STOPEN		(1 << 25)
@@ -174,7 +175,9 @@ void pwm_disable(struct pwm_device *pwm)
 	if (pwm->disable_pwm_pad)
 		pwm->disable_pwm_pad();
 
-	writel(0, pwm->mmio_base + MX3_PWMCR);
+	writel(MX3_PWMCR_SWR, pwm->mmio_base + MX3_PWMCR);
+	while (readl(pwm->mmio_base + MX3_PWMCR) & MX3_PWMCR_SWR)
+		;
 
 	if (pwm->clk_enabled) {
 		clk_disable(pwm->clk);