From: Boris BREZILLON <boris.brezillon@free-electrons.com>
Date: Fri, 6 Jun 2014 21:36:09 +0000 (-0700)
Subject: rtc: rtc-at91rm9200: fix infinite wait for ACKUPD irq
X-Git-Tag: v3.2.61~62
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6df2529a3af404bc367fcf37cd3203c1d4951675;p=pandora-kernel.git

rtc: rtc-at91rm9200: fix infinite wait for ACKUPD irq

commit 2fe121e1f5aa3bf31b418a9790db6c400e922291 upstream.

The rtc user must wait at least 1 sec between each time/calandar update
(see atmel's datasheet chapter "Updating Time/Calendar").

Use the 1Hz interrupt to update the at91_rtc_upd_rdy flag and wait for
the at91_rtc_wait_upd_rdy event if the rtc is not ready.

This patch fixes a deadlock in an uninterruptible wait when the RTC is
updated more than once every second.  AFAICT the bug is here from the
beginning, but I think we should at least backport this fix to 3.10 and
the following longterm and stable releases.

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Reported-by: Bryan Evenson <bevenson@melinkcorp.com>
Tested-by: Bryan Evenson <bevenson@melinkcorp.com>
Cc: Andrew Victor <linux@maxim.org.za>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.2:
 - Adjust context
 - at91_rtc_write() is called at91_sys_write()
 - Use at91_sys_write() directly instead of the missing
   at91_rtc_write_ier() and at91_rtc_write_idr()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

Reading git-diff-tree failed