SMP local timers and their CPUfreq notifiers setup on OMAP3

[Shilimkar, Santosh]

On Sat, Feb 18, 2012 at 12:19 AM, Kevin Hilman <khilman at ti.com> wrote:
> Santosh Shilimkar <santosh.shilimkar at ti.com> writes:
>
>> On Friday 17 February 2012 04:36 PM, Marc Zyngier wrote:
>>> On 17/02/12 10:40, Shilimkar, Santosh wrote:
>>>> On Fri, Feb 17, 2012 at 3:17 PM, Marc Zyngier <marc.zyngier at arm.com> wrote:
>>>>>
>>>>> Hi Santosh,
>>>>>
>>>>> On Fri, 17 Feb 2012 13:18:37 +0530, Santosh Shilimkar
>>>>> <santosh.shilimkar at ti.com> wrote:
>>>>>>
>>>>
>>
>> [..]
>>
>>>> diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
>>>> index 4285daa..265a18a 100644
>>>> --- a/arch/arm/kernel/smp_twd.c
>>>> +++ b/arch/arm/kernel/smp_twd.c
>>>> @@ -129,7 +129,7 @@ static struct notifier_block twd_cpufreq_nb = {
>>>>
>>>>  static int twd_cpufreq_init(void)
>>>>  {
>>>> -   if (!IS_ERR(twd_clk))
>>>> +   if ((!twd_evt) && (!__this_cpu_ptr(twd_evt)) && (!IS_ERR(twd_clk)))
>>>
>>> Erm... Shouldn't that rather be:
>>>      if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
>>>
>> My bad. You are right. Updated patch below.
>> Tested on OMAP3430 SDP with CPUFREQ enabled.
>>
>> Regards
>> Santosh
>>
>> From f58c515a9d1a2c729c05a726d5176843381952ae Mon Sep 17 00:00:00 2001
>> From: Santosh Shilimkar <santosh.shilimkar at ti.com>
>> Date: Fri, 17 Feb 2012 11:11:28 +0530
>> Subject: [PATCH] ARM: smp_twd: Don't register CPUFREQ notifiers if local
>> timers are not initialised.
>>
>> Current ARM local timer code registers CPUFREQ notifiers even in case
>> the twd_timer_setup() isn't called. That seems to be wrong and
>> would eventually lead to kernel crash on the CPU frequency transitions
>> on the SOCs where the local timer doesn't exist or broken because of
>> hardware BUG. Fix it by testing twd_evt and *__this_cpu_ptr(twd_evt).
>>
>> The issue was observed with v3.3-rc3 and building an OMAP2+ kernel
>> on OMAP3 SOC which doesn't have TWD.
>>
>> Below is the dump for reference :
>>
>>  Unable to handle kernel paging request at virtual address 007e900
>>  pgd = cdc20000
>>  [007e9000] *pgd=00000000
>>  Internal error: Oops: 5 [#1] SMP
>>  Modules linked in:
>>  CPU: 0    Not tainted  (3.3.0-rc3-pm+debug+initramfs #9)
>>  PC is at twd_update_frequency+0x34/0x48
>>  LR is at twd_update_frequency+0x10/0x48
>>  pc : [<c001382c>]    lr : [<c0013808>]    psr: 60000093
>>  sp : ce311dd8  ip : 00000000  fp : 00000000
>>  r10: 00000000  r9 : 00000001  r8 : ce310000
>>  r7 : c0440458  r6 : c00137f8  r5 : 00000000  r4 : c0947a74
>>  r3 : 00000000  r2 : 007e9000  r1 : 00000000  r0 : 00000000
>>  Flags: nZCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment usr
>>  Control: 10c5387d  Table: 8dc20019  DAC: 00000015
>>  Process sh (pid: 599, stack limit = 0xce3102f8)
>>  Stack: (0xce311dd8 to 0xce312000)
>>  1dc0:                                                       6000c
>>  1de0: 00000001 00000002 00000000 00000000 00000000 00000000 00000
>>  1e00: ffffffff c093d8f0 00000000 ce311ebc 00000001 00000001 ce310
>>  1e20: c001386c c0437c4c c0e95b60 c0e95ba8 00000001 c0e95bf8 ffff4
>>  1e40: 00000000 00000000 c005ef74 ce310000 c0435cf0 ce311ebc 00000
>>  1e60: ce352b40 0007a120 c08d5108 c08ba040 c08ba040 c005f030 00000
>>  1e80: c08bc554 c032fe2c 0007a120 c08d4b64 ce352b40 c08d8618 ffff8
>>  1ea0: c08ba040 c033364c ce311ecc c0433b50 00000002 ffffffea c0330
>>  1ec0: 0007a120 0007a120 22222201 00000000 22222222 00000000 ce357
>>  1ee0: ce3d6000 cdc2aed8 ce352ba0 c0470164 00000002 c032f47c 00034
>>  1f00: c0331cac ce352b40 00000007 c032f6d0 ce352bbc 0003d090 c0930
>>  1f20: c093d8bc c03306a4 00000007 ce311f80 00000007 cdc2aec0 ce358
>>  1f40: ce8d20c0 00000007 b6fe5000 ce311f80 00000007 ce310000 0000c
>>  1f60: c000de74 ce987400 ce8d20c0 b6fe5000 00000000 00000000 0000c
>>  1f80: 00000000 00000000 001fbac8 00000000 00000007 001fbac8 00004
>>  1fa0: c000df04 c000dd60 00000007 001fbac8 00000001 b6fe5000 00000
>>  1fc0: 00000007 001fbac8 00000007 00000004 b6fe5000 00000000 00202
>>  1fe0: 00000000 beb565f8 00101ffc 00008e8c 60000010 00000001 00000
>>  [<c001382c>] (twd_update_frequency+0x34/0x48) from [<c008ac4c>] )
>>  [<c008ac4c>] (smp_call_function_single+0x17c/0x1c8) from [<c0013)
>>  [<c0013890>] (twd_cpufreq_transition+0x24/0x30) from [<c0437c4c>)
>>  [<c0437c4c>] (notifier_call_chain+0x44/0x84) from [<c005efe4>] ()
>>  [<c005efe4>] (__srcu_notifier_call_chain+0x70/0xa4) from [<c005f)
>>  [<c005f030>] (srcu_notifier_call_chain+0x18/0x20) from [<c032fe2)
>>  [<c032fe2c>] (cpufreq_notify_transition+0xc8/0x1b0) from [<c0333)
>>  [<c033364c>] (omap_target+0x1b4/0x28c) from [<c032f47c>] (__cpuf)
>>  [<c032f47c>] (__cpufreq_driver_target+0x50/0x64) from [<c0331d24)
>>  [<c0331d24>] (cpufreq_set+0x78/0x98) from [<c032f6d0>] (store_sc)
>>  [<c032f6d0>] (store_scaling_setspeed+0x5c/0x74) from [<c03306a4>)
>>  [<c03306a4>] (store+0x58/0x74) from [<c014d868>] (sysfs_write_fi)
>>  [<c014d868>] (sysfs_write_file+0x80/0xb4) from [<c00f2c2c>] (vfs)
>>  [<c00f2c2c>] (vfs_write+0xa8/0x138) from [<c00f2e9c>] (sys_write)
>>  [<c00f2e9c>] (sys_write+0x40/0x6c) from [<c000dd60>] (ret_fast_s)
>>  Code: e594300c e792210c e1a01000 e5840004 (e7930002)
>>  ---[ end trace 5da3b5167c1ecdda ]---
>>
>> Reported-by: Kevin Hilman <khilman at ti.com>
>> Signed-off-by: Santosh Shilimkar <santosh.shilimkar at ti.com>
>
> Tested-by: Kevin Hilman <khilman at ti.com>
>
> CAn you please add to Russell's patch system.  This needs to be fixed
> for v3.3-rc.
>
Done .
7328/1 in patch system.

Regards
Santosh