From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: [PATCH] fix RTC_CLASS regression with PARISC Date: Mon, 8 Sep 2008 17:55:25 -0700 Message-ID: <200809081755.26148.david-b@pacbell.net> References: <1220914847.8074.81.camel@localhost.localdomain> <200809081629.21125.david-b@pacbell.net> <20080908.164427.216880550.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: James.Bottomley@hansenpartnership.com, torvalds@linux-foundation.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org, alessandro.zummo@towertech.it To: David Miller Return-path: In-Reply-To: <20080908.164427.216880550.davem@davemloft.net> List-ID: List-Id: linux-parisc.vger.kernel.org On Monday 08 September 2008, David Miller wrote: > From: David Brownell > Date: Mon, 8 Sep 2008 16:29:20 -0700 > > > That said, there's a bit of unresolved stuff around NTP hooks > > in the kernel. Some patches are pending to let thtem work with > > the RTC framework -- where writing an RTC may need to sleep, > > for example because the RTC is on an I2C or SPI bus. And > > then there's the discussion of whether that shouldn't all be > > handled by NTPD anyway, no special kernel support desired. > > Alessandro has opinions there. ;) > > My update_persistent_clock() on sparc64 is: > > int update_persistent_clock(struct timespec now) > { > struct rtc_device *rtc = rtc_class_open("rtc0"); I'd be tempted to cache that ... notice how you never close it, too. That will goof lots of refcounts... > if (rtc) > return rtc_set_mmss(rtc, now.tv_sec); > > return -1; > } > > and that should handle this NTP shouldn't it? Depends on what patches have applied; I've lost track of whether it's now ok for update_persistent_clock() to sleep. Previously it was not, without a critical patch (appended). Having something like that work is *certainly* a goal, at least for those who don't want to get rid of those kernel NTP hooks entirely. And of course, once that works I'd claim it should live in drivers/rtc for the benefit of other platforms. :) - Dave =============== CUT ON THE DOTTED LINE ================== Subject: ntp: let update_persistent_clock() sleep From: "Maciej W. Rozycki" This is a change that makes the 11-minute RTC update be run in the process context. This is so that update_persistent_clock() can sleep, which may be required for certain types of RTC hardware -- most notably I2C devices. Signed-off-by: Maciej W. Rozycki Cc: Thomas Gleixner Cc: Roman Zippel Cc: Rik van Riel Cc: Alessandro Zummo Cc: David Brownell Signed-off-by: Andrew Morton --- kernel/time/ntp.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/kernel/time/ntp.c 2008-06-30 21:20:51.000000000 -0700 +++ b/kernel/time/ntp.c 2008-06-30 21:21:27.000000000 -0700 @@ -10,13 +10,13 @@ #include #include -#include #include #include #include #include #include #include +#include #include /* @@ -218,11 +218,11 @@ void second_overflow(void) /* Disable the cmos update - used by virtualization and embedded */ int no_sync_cmos_clock __read_mostly; -static void sync_cmos_clock(unsigned long dummy); +static void sync_cmos_clock(struct work_struct *work); -static DEFINE_TIMER(sync_cmos_timer, sync_cmos_clock, 0, 0); +static DECLARE_DELAYED_WORK(sync_cmos_work, sync_cmos_clock); -static void sync_cmos_clock(unsigned long dummy) +static void sync_cmos_clock(struct work_struct *work) { struct timespec now, next; int fail = 1; @@ -258,13 +258,13 @@ static void sync_cmos_clock(unsigned lon next.tv_sec++; next.tv_nsec -= NSEC_PER_SEC; } - mod_timer(&sync_cmos_timer, jiffies + timespec_to_jiffies(&next)); + schedule_delayed_work(&sync_cmos_work, timespec_to_jiffies(&next)); } static void notify_cmos_timer(void) { if (!no_sync_cmos_clock) - mod_timer(&sync_cmos_timer, jiffies + 1); + schedule_delayed_work(&sync_cmos_work, 0); } #else