Messages in this thread | | | Date | Thu, 20 Nov 2014 09:49:00 +0100 | From | Maxime Ripard <> | Subject | Re: [PATCH v4] clocksource: arch_timer: Fix code to use physical timers when requested |
| |
Hi,
On Wed, Oct 08, 2014 at 12:38:57AM -0700, Sonny Rao wrote: > This is a bug fix for using physical arch timers when > the arch_timer_use_virtual boolean is false. It restores the > arch_counter_get_cntpct() function after removal in > > 0d651e4e "clocksource: arch_timer: use virtual counters" > > We need this on certain ARMv7 systems which are architected like this: > > * The firmware doesn't know and doesn't care about hypervisor mode and > we don't want to add the complexity of hypervisor there. > > * The firmware isn't involved in SMP bringup or resume. > > * The ARCH timer come up with an uninitialized offset between the > virtual and physical counters. Each core gets a different random > offset. > > * The device boots in "Secure SVC" mode. > > * Nothing has touched the reset value of CNTHCTL.PL1PCEN or > CNTHCTL.PL1PCTEN (both default to 1 at reset) > > One example of such as system is RK3288 where it is much simpler to > use the physical counter since there's nobody managing the offset and > each time a core goes down and comes back up it will get reinitialized > to some other random value. > > Fixes: 0d651e4e65e9 ("clocksource: arch_timer: use virtual counters") > Cc: stable@vger.kernel.org > Signed-off-by: Sonny Rao <sonnyrao@chromium.org> > Acked-by: Olof Johansson <olof@lixom.net>
Has this been merged yet?
If not, you can add my Tested-by, it makes the Allwinner A31 boot flawlessly with the arch timers (together with the patch "clocksource: arch_timer: Allow the device tree to specify uninitialized timer registers")
Thanks! Maxime
Maxime
-- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com [unhandled content-type:application/pgp-signature] | |