From mboxrd@z Thu Jan 1 00:00:00 1970 From: boris.brezillon@free-electrons.com (Boris BREZILLON) Date: Tue, 06 May 2014 22:43:36 +0200 Subject: [PATCH] rtc: rtc-at91rm9200: fix infinite wait for ACKUPD irq In-Reply-To: References: <94c06375c1b44c8eb5233b0ccf2e4b13@BY2PR05MB048.namprd05.prod.outlook.com> <1399386481-18643-1-git-send-email-boris.brezillon@free-electrons.com> Message-ID: <53694978.3050303@free-electrons.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, On 06/05/2014 21:06, Bryan Evenson wrote: > Boris, > >> -----Original Message----- >> From: Boris BREZILLON [mailto:boris.brezillon at free-electrons.com] >> Sent: Tuesday, May 06, 2014 10:28 AM >> To: Bryan Evenson >> Cc: Andrew Victor; Nicolas Ferre; Jean-Christophe Plagniol-Villard; linux-arm- >> kernel at lists.infradead.org; Alessandro Zummo; rtc- >> linux at googlegroups.com; linux-kernel at vger.kernel.org; Boris BREZILLON >> Subject: [PATCH] rtc: rtc-at91rm9200: fix infinite wait for ACKUPD irq >> >> 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. >> >> Signed-off-by: Boris BREZILLON >> Reported-by: Bryan Evenson >> --- >> Hello Bryan, >> >> I reproduced your bug (using your script) and this patch seems to fix the >> problem. >> >> Could you try it and let me know if it works for you ? > Looks good to me. I modified the test script as follows: > > ---------- > #!/bin/sh > i=0 > while [ 1 ]; do > hwclock -w -u > /dev/null 2>&1 > echo $$ $i $? > : $((i++)) > done > ---------- > > This version then attempts to write to the RTC as often as possible (script change was due to a suggestion on the Busybox mailing list). I ran two instances of the script, which each looped through about 60,000 times over a 30 minute run. At no point has access to the RTC been permanently locked out on my system. I'd call this fixed. Great! > I'd assume this patch would be backported to the longterm releases? I'd like to wait for Nicolas' ack before asking for a backport to stable releases. Best Regards, Boris -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com