From: kgene.kim@samsung.com (Kukjin Kim) Date: Wed, 04 Jun 2014 10:47:22 +0900 Subject: [PATCH] arm: mct: Don't reset the counter during boot and resume In-Reply-To: References: <1401821299-24431-1-git-send-email-chirantan@chromium.org> Message-ID: <026701cf7f96$ed616a00$c8243e00$@samsung.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Doug Anderson wrote: > > Chirantan, > > On Tue, Jun 3, 2014 at 11:48 AM, Chirantan Ekbote > wrote: > > Unfortunately on some exynos systems, resetting the mct counter also > > resets the architected timer counter. This can cause problems if the > > architected timer driver has already been initialized because the kernel > > will think that the counter has wrapped around, causing a big jump in > > printk timestamps and delaying any scheduled clock events until the > > counter reaches the value it had before it was reset. > > > > The kernel code makes no assumptions about the initial value of the mct > > counter so there is no reason from a software perspective to clear the > > counter before starting it. This also fixes the problems described in > > the previous paragraph. > > > > Cc: Olof Johansson > > Cc: Doug Anderson > > Cc: Kukjin Kim > > Cc: Tomasz Figa > > Cc: linux-arm-kernel at lists.infradead.org > > Cc: linux-samsung-soc at vger.kernel.org > > Signed-off-by: Chirantan Ekbote > > --- > > drivers/clocksource/exynos_mct.c | 9 +++------ > > 1 file changed, 3 insertions(+), 6 deletions(-) > > I can confirm that this fixes problems I described in > . Now > when I boot there's no mysterious delay and there's no big jump in > time. > > I'd love to see this in 3.16 so we can get rid of this annoying delay. > > Reviewed-by: Doug Anderson > Tested-by: Doug Anderson OK, I will queue this patch into fixes for 3.16. Thanks, Kukjin