Enable arm_global_timer for Zynq brakes boot
From: Stephen Boyd <hidden>
Date: 2013-08-12 16:20:23
Also in:
lkml
Subsystem:
nohz, dynticks support, the rest · Maintainers:
Anna-Maria Behnsen, Frederic Weisbecker, Ingo Molnar, Thomas Gleixner, Linus Torvalds
On 08/12/13 09:03, S?ren Brinkmann wrote:
On Fri, Aug 09, 2013 at 10:27:57AM -0700, Stephen Boyd wrote:quoted
On 08/09, Daniel Lezcano wrote:quoted
yes, but at least the broadcast mechanism should send an IPI to cpu0 to wake it up, no ? As Stephen stated this kind of configuration should has never been tested before so the tick broadcast code is not handling this case properly IMHO.If you have a per-cpu tick device that isn't suffering from FEAT_C3_STOP why wouldn't you use that for the tick versus a per-cpu tick device that has FEAT_C3_STOP? It sounds like there is a bug in the preference logic or you should boost the rating of the arm global timer above the twd. Does this patch help? It should make the arm global timer the tick device and whatever the cadence timer you have into the broadcast device.I finally got to test your patch. Unfortunately, it makes the system hang even earlier:
Sorry it had a bug depending on the registration order. Can you try this one (tabs are probably spaces, sorry)? I will go read through this thread to see if we already covered the registration order. ---8<----
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 218bcb5..d3539e5 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c@@ -77,6 +77,9 @@ static bool tick_check_broadcast_device(struct clock_event_device *curdev, !(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) return false; + if (cpumask_equal(newdev->cpumask, cpumask_of(smp_processor_id()))) + return false; + return !curdev || newdev->rating > curdev->rating; }
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 64522ec..dd08f3b 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c@@ -244,12 +244,22 @@ static bool tick_check_preferred(struct clock_event_device *curdev, return false; } + if (!curdev) + return true; + + /* Always prefer a tick device that doesn't suffer from FEAT_C3STOP */ + if (!(newdev->features & CLOCK_EVT_FEAT_C3STOP) && + (curdev->features & CLOCK_EVT_FEAT_C3STOP)) + return true; + if ((newdev->features & CLOCK_EVT_FEAT_C3STOP) && + !(curdev->features & CLOCK_EVT_FEAT_C3STOP)) + return false; + /* * Use the higher rated one, but prefer a CPU local device with a lower * rating than a non-CPU local device */ - return !curdev || - newdev->rating > curdev->rating || + return newdev->rating > curdev->rating || !cpumask_equal(curdev->cpumask, newdev->cpumask); }
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