BMC/Intel-BMC/linux.git/kernel/time/clockevents.c, branch dev

clockevents: Allow set-state callbacks to be optional

2015-07-07T08:44:45+00:00

Its mandatory for the drivers to provide set_state_{oneshot|periodic}() (only if related modes are supported) and set_state_shutdown() callbacks today, if they are implementing the new set-state interface. But this leads to unnecessary noop callbacks for drivers which don't want to implement them. Over that, it will lead to a full function call for nothing really useful. Lets make all set-state callbacks optional. Suggested-by: Daniel Lezcano Signed-off-by: Viresh Kumar Signed-off-by: Daniel Lezcano Link: http://lkml.kernel.org/r/1436256875-15562-1-git-send-email-daniel.lezcano@linaro.org Signed-off-by: Thomas Gleixner

clockevents: Check state instead of mode in suspend/resume path

2015-06-18T07:27:02+00:00

CLOCK_EVT_MODE_* macros are present for backward compatibility (as most of the drivers are still using old ->set_mode() interface). These macro's shouldn't be used anymore in code, that is common to both driver interfaces, i.e. ->set_mode() and ->set_state_*(). Drivers implementing ->set_state_*() interface, which have their clkevt->mode set to 0 (clkevt device structures are normally globally defined), will not participate in suspend/resume as they will always be marked as UNUSED. Fix this by checking state of the clockevent device instead of mode, which is updated for both the interfaces. Fixes: ac34ad27fc16 ("clockevents: Do not suspend/resume if unused") Signed-off-by: Viresh Kumar Cc: linaro-kernel@lists.linaro.org Cc: alexandre.belloni@free-electrons.com Cc: sylvain.rochet@finsecur.com Link: http://lkml.kernel.org/r/a1964eef6e8a47d02b1ff9083c6c91f73f0ff643.1434537215.git.viresh.kumar@linaro.org Signed-off-by: Thomas Gleixner

clockevents: Use set/get state helper functions

2015-06-02T12:40:48+00:00

Signed-off-by: Thomas Gleixner Cc: Viresh Kumar Cc: Peter Zijlstra

clockevents: Provide functions to set and get the state

2015-06-02T12:40:47+00:00

We want to rename dev->state, so provide proper get and set functions. Rename clockevents_set_state() to clockevents_switch_state() to avoid confusion. Signed-off-by: Thomas Gleixner Cc: Viresh Kumar Cc: Peter Zijlstra

clockevents: Use helpers to check the state of a clockevent device

2015-06-02T12:40:47+00:00

Use accessor functions to check the state of clockevent devices in core code. Signed-off-by: Viresh Kumar Cc: linaro-kernel@lists.linaro.org Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/fa2b9869fd17f210eaa156ec2b594efd0230b6c7.1432192527.git.viresh.kumar@linaro.org Signed-off-by: Thomas Gleixner

clockevents: Do not suspend/resume if unused

2015-05-26T23:03:38+00:00

There is no point in calling suspend/resume for unused clockevents as they are already stopped and disabled. This is really important for AT91 as the hardware is a trainwreck and takes ages to synchronize. Reported-by: Sylvain Rochet Signed-off-by: Alexandre Belloni Cc: Daniel Lezcano Cc: Nicolas Ferre Cc: Boris Brezillon Cc: Maxime Ripard Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/1421399151-26800-1-git-send-email-alexandre.belloni@free-electrons.com Signed-off-by: Thomas Gleixner

clockevents: Stop unused clockevent devices

2015-05-19T14:18:11+00:00

To avoid getting spurious interrupts on a tickless CPU, clockevent device can now be stopped by switching to ONESHOT_STOPPED state. The natural place for handling this transition is tick_program_event(). On 'expires == KTIME_MAX', we skip programming the event and so we need to fix such call sites as well, to always call tick_program_event() irrespective of the expires value. Once the clockevent device is required again, check if it was earlier put into ONESHOT_STOPPED state. If yes, switch its state to ONESHOT before programming its event. To make sure we haven't missed any corner case, add a WARN() for the case where we try to reprogram clockevent device while we aren't configured in ONESHOT_STOPPED state. Signed-off-by: Viresh Kumar Cc: linaro-kernel@lists.linaro.org Cc: Frederic Weisbecker Cc: Kevin Hilman Cc: Daniel Lezcano Cc: Preeti U Murthy Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/5146b07be7f0bc497e0ebae036590ec2fa73e540.1428031396.git.viresh.kumar@linaro.org Signed-off-by: Thomas Gleixner

clockevents: Introduce CLOCK_EVT_STATE_ONESHOT_STOPPED state

2015-05-19T14:18:02+00:00

When no timers/hrtimers are pending, the expiry time is set to a special value: 'KTIME_MAX'. This normally happens with NO_HZ_{IDLE|FULL} in both LOWRES/HIGHRES modes. When 'expiry == KTIME_MAX', we either cancel the 'tick-sched' hrtimer (NOHZ_MODE_HIGHRES) or skip reprogramming clockevent device (NOHZ_MODE_LOWRES). But, the clockevent device is already reprogrammed from the tick-handler for next tick. As the clock event device is programmed in ONESHOT mode it will at least fire one more time (unnecessarily). Timers on few implementations (like arm_arch_timer, etc.) only support PERIODIC mode and their drivers emulate ONESHOT over that. Which means that on these platforms we will get spurious interrupts periodically (at last programmed interval rate, normally tick rate). In order to avoid spurious interrupts, the clockevent device should be stopped or its interrupts should be masked. A simple (yet hacky) solution to get this fixed could be: update hrtimer_force_reprogram() to always reprogram clockevent device and update clockevent drivers to STOP generating events (or delay it to max time) when 'expires' is set to KTIME_MAX. But the drawback here is that every clockevent driver has to be hacked for this particular case and its very easy for new ones to miss this. However, Thomas suggested to add an optional state ONESHOT_STOPPED to solve this problem: lkml.org/lkml/2014/5/9/508. This patch adds support for ONESHOT_STOPPED state in clockevents core. It will only be available to drivers that implement the state-specific callbacks instead of the legacy ->set_mode() callback. Signed-off-by: Viresh Kumar Reviewed-by: Preeti U. Murthy Cc: linaro-kernel@lists.linaro.org Cc: Frederic Weisbecker Cc: Kevin Hilman Cc: Daniel Lezcano Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/b8b383a03ac07b13312c16850b5106b82e4245b5.1428031396.git.viresh.kumar@linaro.org Signed-off-by: Thomas Gleixner

Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-05-09T21:57:49+00:00

Pull timer fix from Thomas Gleixner: "A simple fix to actually shut down a detached device instead of keeping it active" * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: clockevents: Shutdown detached clockevent device

clockevents: Shutdown detached clockevent device

2015-04-24T19:01:48+00:00

A clockevent device is marked DETACHED when it is replaced by another clockevent device. The device is shutdown properly for drivers that implement legacy ->set_mode() callback, as we call ->set_mode() for CLOCK_EVT_MODE_UNUSED as well. But for the new per-state callback interface, we skip shutting down the device, as we thought its an internal state change. That wasn't correct. The effect is that the device is left programmed in oneshot or periodic mode. Fall-back to 'case CLOCK_EVT_STATE_SHUTDOWN', to shutdown the device. Fixes: bd624d75db21 "clockevents: Introduce mode specific callbacks" Reported-by: Daniel Lezcano Signed-off-by: Viresh Kumar Cc: linaro-kernel@lists.linaro.org Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/eef0a91c51b74d4e52c8e5a95eca27b5a0563f07.1428650683.git.viresh.kumar@linaro.org Signed-off-by: Thomas Gleixner