linux-kernel - [PATCH 4/4] Blackfin RTC Driver: dont let RTC programming in bootloaders randomly cause ~5 second boot delays

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Message-Id: <1218790880-12477-5-git-send-email-cooloney@kernel.org>
Date:	Fri, 15 Aug 2008 17:01:20 +0800
From:	Bryan Wu <cooloney@...nel.org>
To:	a.zummo@...ertech.it, rtc-linux@...glegroups.com
Cc:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	Mike Frysinger <vapier.adi@...il.com>,
	Bryan Wu <cooloney@...nel.org>
Subject: [PATCH 4/4] Blackfin RTC Driver: dont let RTC programming in bootloaders randomly cause ~5 second boot delays

From: Mike Frysinger <vapier.adi@...il.com>

Signed-off-by: Mike Frysinger <vapier.adi@...il.com>
Signed-off-by: Bryan Wu <cooloney@...nel.org>
---
 drivers/rtc/rtc-bfin.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/drivers/rtc/rtc-bfin.c b/drivers/rtc/rtc-bfin.c
index 9d2da1c..34439ce 100644
--- a/drivers/rtc/rtc-bfin.c
+++ b/drivers/rtc/rtc-bfin.c
@@ -363,6 +363,7 @@ static int __devinit bfin_rtc_probe(struct platform_device *pdev)
 	struct bfin_rtc *rtc;
 	struct device *dev = &pdev->dev;
 	int ret = 0;
+	unsigned long timeout;
 
 	dev_dbg_stamp(dev);
 
@@ -377,6 +378,13 @@ static int __devinit bfin_rtc_probe(struct platform_device *pdev)
 	ret = request_irq(IRQ_RTC, bfin_rtc_interrupt, IRQF_SHARED, pdev->name, dev);
 	if (unlikely(ret))
 		goto err;
+	/* sometimes the bootloader touched things, but the write complete was not
+	 * enabled, so let's just do a quick timeout here since the IRQ will not fire ...
+	 */
+	timeout = jiffies + HZ;
+	while (bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_PENDING)
+		if (time_after(jiffies, timeout))
+			break;
 	bfin_rtc_reset(dev, RTC_ISTAT_WRITE_COMPLETE);
 	bfin_write_RTC_SWCNT(0);
 
-- 
1.5.6
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