[PATCH] rtc: snvs: improve timeout handling in snvs_rtc_enable()

[Lothar Waßmann]

If snvs_rtc_enable() happens to be descheduled for a period longer
than the timout period, a timeout may be indicated even if the RTC
status has changed meanwhile. Force a status read at the end of the
timeout period to prevent bogus timeout errors.


Signed-off-by: Lothar Waßmann <LW at KARO-electronics.de>
---
 drivers/rtc/rtc-snvs.c |   22 +++++++++++++---------
 1 files changed, 13 insertions(+), 9 deletions(-)

 Compile tested only due to lack of HW.

diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c
index 912f116..dc921b2 100644
--- a/drivers/rtc/rtc-snvs.c
+++ b/drivers/rtc/rtc-snvs.c
@@ -81,6 +81,13 @@ static void rtc_write_sync_lp(void __iomem *ioaddr)
 	}
 }
 
+static int snvs_rtc_enable_done(int enable, void __iomem *addr)
+{
+	u32 lpcr = readl(addr + SNVS_LPCR);
+
+	return !!enable ^ !(lpcr & SNVS_LPCR_SRTC_ENV);
+}
+
 static int snvs_rtc_enable(struct snvs_rtc_data *data, bool enable)
 {
 	unsigned long timeout = jiffies + msecs_to_jiffies(1);
@@ -99,18 +106,15 @@ static int snvs_rtc_enable(struct snvs_rtc_data *data, bool enable)
 	spin_unlock_irqrestore(&data->lock, flags);
 
 	while (1) {
-		lpcr = readl(data->ioaddr + SNVS_LPCR);
+		if (snvs_rtc_enable_done(enable, data->ioaddr))
+			break;
 
-		if (enable) {
-			if (lpcr & SNVS_LPCR_SRTC_ENV)
-				break;
-		} else {
-			if (!(lpcr & SNVS_LPCR_SRTC_ENV))
+		if (time_after(jiffies, timeout)) {
+			if (snvs_rtc_enable_done(enable, data->ioaddr))
 				break;
+			else
+				return -ETIMEDOUT;
 		}
-
-		if (time_after(jiffies, timeout))
-			return -ETIMEDOUT;
 	}
 
 	return 0;
-- 
1.7.2.5