On Fri, Aug 09, 2013 at 10:27:57AM -0700, Stephen Boyd wrote:
> On 08/09, Daniel Lezcano wrote:
> >
> > 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:
Starting kernel ...
Uncompressing Linux... done, booting the kernel.
[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Linux version 3.11.0-rc3-00002-g391ac9b
(sorenb@xsjandreislx) (gcc version 4.7.2 (Sourcery CodeBench Lite 2012.09-104)
) #98 SMP PREEMPT Mon Aug 12 08:59:34 PDT 2013
[ 0.000000] CPU: ARMv7 Processor [413fc090] revision 0 (ARMv7),
cr=18c5387d
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing
instruction cache
[ 0.000000] Machine: Xilinx Zynq Platform, model: Zynq ZC706
Development Board
[ 0.000000] bootconsole [earlycon0] enabled
[ 0.000000] cma: CMA: reserved 16 MiB at 2e800000
[ 0.000000] Memory policy: ECC disabled, Data cache writealloc
[ 0.000000] PERCPU: Embedded 9 pages/cpu @c149c000 s14720 r8192
d13952 u36864
[ 0.000000] Built 1 zonelists in Zone order, mobility grouping on.
Total pages: 260624
[ 0.000000] Kernel command line: console=ttyPS0,115200 earlyprintk
[ 0.000000] PID hash table entries: 4096 (order: 2, 16384 bytes)
[ 0.000000] Dentry cache hash table entries: 131072 (order: 7,
524288 bytes)
[ 0.000000] Inode-cache hash table entries: 65536 (order: 6, 262144
bytes)
[ 0.000000] Memory: 1004928K/1048576K available (4891K kernel code,
307K rwdata, 1564K rodata, 338K init, 5699K bss, 43648K reserved, 270336K
highmem)
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB)
[ 0.000000] fixmap : 0xfff00000 - 0xfffe0000 ( 896 kB)
[ 0.000000] vmalloc : 0xf0000000 - 0xff000000 ( 240 MB)
[ 0.000000] lowmem : 0xc0000000 - 0xef800000 ( 760 MB)
[ 0.000000] pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB)
[ 0.000000] modules : 0xbf000000 - 0xbfe00000 ( 14 MB)
[ 0.000000] .text : 0xc0008000 - 0xc0656128 (6457 kB)
[ 0.000000] .init : 0xc0657000 - 0xc06ab980 ( 339 kB)
[ 0.000000] .data : 0xc06ac000 - 0xc06f8c20 ( 308 kB)
[ 0.000000] .bss : 0xc06f8c20 - 0xc0c89aa4 (5700 kB)
[ 0.000000] Preemptible hierarchical RCU implementation.
[ 0.000000] RCU lockdep checking is enabled.
[ 0.000000] Additional per-CPU info printed with stalls.
[ 0.000000] RCU restricting CPUs from NR_CPUS=4 to nr_cpu_ids=2.
[ 0.000000] NR_IRQS:16 nr_irqs:16 16
[ 0.000000] slcr mapped to f0004000
[ 0.000000] Zynq clock init
[ 0.000000] sched_clock: 32 bits at 333MHz, resolution 3ns, wraps
every 12884ms
[ 0.000000] ttc0 #0 at f0006000, irq=43
[ 0.000000] Console: colour dummy device 80x30
[ 0.000000] Lock dependency validator: Copyright (c) 2006 Red Hat,
Inc., Ingo Molnar
[ 0.000000] ... MAX_LOCKDEP_SUBCLASSES: 8
[ 0.000000] ... MAX_LOCK_DEPTH: 48
[ 0.000000] ... MAX_LOCKDEP_KEYS: 8191
[ 0.000000] ... CLASSHASH_SIZE: 4096
[ 0.000000] ... MAX_LOCKDEP_ENTRIES: 16384
[ 0.000000] ... MAX_LOCKDEP_CHAINS: 32768
[ 0.000000] ... CHAINHASH_SIZE: 16384
[ 0.000000] memory used by lock dependency info: 3695 kB
[ 0.000000] per task-struct memory footprint: 1152 bytes
[ 0.057541] Calibrating delay loop... 1325.46 BogoMIPS (lpj=6627328)
[ 0.100248] pid_max: default: 32768 minimum: 301
[ 0.103294] Mount-cache hash table entries: 512
[ 0.114364] CPU: Testing write buffer coherency: ok
[ 0.114513] ftrace: allocating 16143 entries in 48 pages
[ 0.155012] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
Sören
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