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Re: SMTC support status in latest git head.

To: Anoop P A <anoop.pa@gmail.com>
Subject: Re: SMTC support status in latest git head.
From: "Kevin D. Kissell" <kevink@paralogos.com>
Date: Wed, 15 Dec 2010 11:58:38 -0800
Cc: "Anoop P.A." <Anoop_P.A@pmc-sierra.com>, linux-mips@linux-mips.org
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On 12/15/10 11:18, Anoop P A wrote:
On Tue, 2010-12-14 at 10:32 -0800, Kevin D. Kissell wrote:

I can't comment on your tweak to 2.6.24.7 without seeing it as a patch
diff.
http://patchwork.linux-mips.org/patch/804/ I was speaking about this
patch. Since my timer is connected through a cascaded CIC , It is
required to check TI bit of cause register in order to ensure a timer
interrupt. With above mentioned patch I was able to boot a 2.6.24-stable
SMTC kernel. ( Not tested fully though )
OK, yes, of course, you'd need that patch.
The recommended procedure was, and remains, to isolate clock
propagation problems by using command line options "maxtcs="
and "maxvpes=".

First, boot your SMTC kernel with maxtcs=1 and maxvpes=1,
a virtual uniprocessor.  If that doesn't run, you've got some fundamental
problem with support for your platform, or someone has really fundamentally
broken the SMTC build somewhere.  Next, try booting with maxtcs=2
and maxvpes=1, then with no constraint on maxtcs and maxvpes=1.
If those fail, your problem is probably in the interrupt mask
management algorithms I described
Even with command line maxtcs=1 and maxvpes=1 I am seeing same hung. The
register dump is copied below.
I guess what jumps out at me is that VPE0.EPC doesn't look to have
changed since the very initial boot vector, as if we'd never successfully
taken an exception or interrupt of any kind, prior to the NMI (I'm assuming
you're getting that MT state dump by breaking in with an NMI).
I'm puzzled that TC0.TCStatus is being reported as 0, when it should
have a bunch of bits in common with VPE0.Status.  And I'm particularly
intrigued by the fact that you seem to have an interrupt bit set in Cause
which is enabled in Status, with IE set and EXL/ERL clear, yet you don't
seem to be getting interrupts.

Do you have access to some kind of EJTAG probe for your system?

I have tested few stable tags in git and isolated the code brake.

2.6.24-stable + patch[1] = SMTC boot success
2.6.29-stable + patch[1] = SMTC boot success
2.6.31-stable + patch[1] = SMTC boot success
2.6.32-stable + patch[1] = SMTC boot success
2.6.33-stable            = SMTC boot failed
2.6.35-stable            = SMTC boot failed

So it looks like SMTC support got broke between 2.6.32 and 2.6.33 .
That's a pretty good job of isolating the problem, and the fact
that it happens even with no TC or VPE concurrency means it's
not a failure of the SMTC logic per se, but that someone changed
some code that's common to SMTC and "normal"/SMP operation
in a way that breaks the more constrained assumptions of SMTC.

Thanks and Regards,
Anoop

patch[1] : http://patchwork.linux-mips.org/patch/804/


#############################Log###########################
     0.000000] Calibrating delay loop... === MIPS MT State Dump ===
[    0.000000] -- Global State --
[    0.000000]    MVPControl Passed: 00000000
[    0.000000]    MVPControl Read: 00000000
[    0.000000]    MVPConf0 : a8008406
[    0.000000] -- per-VPE State --
[    0.000000]   VPE 0
[    0.000000]    VPEControl : 00000000
[    0.000000]    VPEConf0 : 800f0003
[    0.000000]    VPE0.Status : 11004001
[    0.000000]    VPE0.EPC : 80100000 _stext+0x0/0x10
[    0.000000]    VPE0.Cause : 50804000
[    0.000000]    VPE0.Config7 : 00010000
[    0.000000]   VPE 1
[    0.000000]    VPEControl : 00060000
[    0.000000]    VPEConf0 : 800f0000
[    0.000000]    VPE1.Status : 00408305
[    0.000000]    VPE1.EPC : 80100380 name_to_dev_t+0x50/0x430
[    0.000000]    VPE1.Cause : 50000200
[    0.000000]    VPE1.Config7 : 00010000
[    0.000000] -- per-TC State --
[    0.000000]   TC 0 (current TC with VPE EPC above)
[    0.000000]    TCStatus : 00000000
[    0.000000]    TCBind : 00000000
[    0.000000]    TCRestart : 8010d860 mips_mt_regdump+0x2f0/0x3c4
[    0.000000]    TCHalt : 00000000
[    0.000000]    TCContext : 00000000
[    0.000000]   TC 1
[    0.000000]    TCStatus : 00000000
[    0.000000]    TCBind : 00200001
[    0.000000]    TCRestart : 8f800020 0x8f800020
[    0.000000]    TCHalt : 00000001
[    0.000000]    TCContext : 00140000
[    0.000000]   TC 2
[    0.000000]    TCStatus : 00000000
[    0.000000]    TCBind : 00400001
[    0.000000]    TCRestart : 8f800020 0x8f800020
[    0.000000]    TCHalt : 00000001
[    0.000000]    TCContext : 00280000
[    0.000000]   TC 3
[    0.000000]    TCStatus : 00000000
[    0.000000]    TCBind : 00600001
[    0.000000]    TCRestart : 8f800020 0x8f800020
[    0.000000]    TCHalt : 00000001
[    0.000000]    TCContext : 003c0000
[    0.000000]   TC 4
[    0.000000]    TCStatus : 00000000
[    0.000000]    TCBind : 00800001
[    0.000000]    TCRestart : 80100380 name_to_dev_t+0x50/0x430
[    0.000000]    TCHalt : 00000001
[    0.000000]    TCContext : 00500000
[    0.000000]   TC 5
[    0.000000]    TCStatus : 00000000
[    0.000000]    TCBind : 00a00001
[    0.000000]    TCRestart : 80100380 name_to_dev_t+0x50/0x430
[    0.000000]    TCHalt : 00000001
[    0.000000]    TCContext : 00640000
[    0.000000]   TC 6
[    0.000000]    TCStatus : 00000000
[    0.000000]    TCBind : 00c00001
[    0.000000]    TCRestart : 80268e00 aes_encrypt+0x10e4/0x164c
[    0.000000]    TCHalt : 00000001
[    0.000000]    TCContext : 00780000
[    0.000000] Counter Interrupts taken per CPU (TC)
[    0.000000] 0: 0
[    0.000000] 1: 0
[    0.000000] 2: 0
[    0.000000] 3: 0
[    0.000000] 4: 0
[    0.000000] 5: 0
[    0.000000] 6: 0
[    0.000000] 7: 0
[    0.000000] Self-IPI invocations:
[    0.000000] 0: 0
[    0.000000] 1: 0
[    0.000000] 2: 0
[    0.000000] 3: 0
[    0.000000] 4: 0
[    0.000000] 5: 0
[    0.000000] 6: 0
[    0.000000] 7: 0
[    0.000000] IPIQ[0]: head = 0x0, tail = 0x0, depth = 0
[    0.000000] IPIQ[1]: head = 0x0, tail = 0x0, depth = 0
[    0.000000] IPIQ[2]: head = 0x0, tail = 0x0, depth = 0
[    0.000000] IPIQ[3]: head = 0x0, tail = 0x0, depth = 0
[    0.000000] IPIQ[4]: head = 0x0, tail = 0x0, depth = 0
[    0.000000] IPIQ[5]: head = 0x0, tail = 0x0, depth = 0
[    0.000000] IPIQ[6]: head = 0x0, tail = 0x0, depth = 0
[    0.000000] IPIQ[7]: head = 0x0, tail = 0x0, depth = 0
[    0.000000] 0 Recoveries of "stolen" FPU
[    0.000000] ===========================
[    0.000000] In platform cic dispatch cic_mask=0x22000 stat=0x2402000f
pend=0x20000
[    0.010000] === MIPS MT State Dump ===
[    0.010000] -- Global State --
[    0.010000]    MVPControl Passed: 00000000
[    0.010000]    MVPControl Read: 00000000
[    0.010000]    MVPConf0 : a8008406
[    0.010000] -- per-VPE State --
[    0.010000]   VPE 0
[    0.010000]    VPEControl : 00000000
[    0.010000]    VPEConf0 : 800f0003
[    0.010000]    VPE0.Status : 18004000
[    0.010000]    VPE0.EPC : 8010d900 mips_mt_regdump+0x390/0x3c4
[    0.010000]    VPE0.Cause : 40804000
[    0.010000]    VPE0.Config7 : 00010000
[    0.010000]   VPE 1
[    0.010000]    VPEControl : 00060000
[    0.010000]    VPEConf0 : 800f0000
[    0.010000]    VPE1.Status : 00408305
[    0.010000]    VPE1.EPC : 80100380 name_to_dev_t+0x50/0x430
[    0.010000]    VPE1.Cause : 50000200
[    0.010000]    VPE1.Config7 : 00010000
[    0.010000] -- per-TC State --
[    0.010000]   TC 0 (current TC with VPE EPC above)
[    0.010000]    TCStatus : 00000000
[    0.010000]    TCBind : 00000000
[    0.010000]    TCRestart : 803f791c printk+0xc/0x30
[    0.010000]    TCHalt : 00000000
[    0.010000]    TCContext : 00000000
[    0.010000]   TC 1
[    0.010000]    TCStatus : 00000000
[    0.010000]    TCBind : 00200001
[    0.010000]    TCRestart : 8f800020 0x8f800020
[    0.010000]    TCHalt : 00000001
[    0.010000]    TCContext : 00140000
[    0.010000]   TC 2
[    0.010000]    TCStatus : 00000000
[    0.010000]    TCBind : 00400001
[    0.010000]    TCRestart : 8f800020 0x8f800020
[    0.010000]    TCHalt : 00000001
[    0.010000]    TCContext : 00280000
[    0.010000]   TC 3
[    0.010000]    TCStatus : 00000000
[    0.010000]    TCBind : 00600001
[    0.010000]    TCRestart : 8f800020 0x8f800020
[    0.010000]    TCHalt : 00000001
[    0.010000]    TCContext : 003c0000
[    0.010000]   TC 4
[    0.010000]    TCStatus : 00000000
[    0.010000]    TCBind : 00800001
[    0.010000]    TCRestart : 80100380 name_to_dev_t+0x50/0x430
[    0.010000]    TCHalt : 00000001
[    0.010000]    TCContext : 00500000
[    0.010000]   TC 5
[    0.010000]    TCStatus : 00000000
[    0.010000]    TCBind : 00a00001
[    0.010000]    TCRestart : 80100380 name_to_dev_t+0x50/0x430
[    0.010000]    TCHalt : 00000001
[    0.010000]    TCContext : 00640000
[    0.010000]   TC 6
[    0.010000]    TCStatus : 00000000
[    0.010000]    TCBind : 00c00001
[    0.010000]    TCRestart : 80268e00 aes_encrypt+0x10e4/0x164c
[    0.010000]    TCHalt : 00000001
[    0.010000]    TCContext : 00780000
[    0.010000] Counter Interrupts taken per CPU (TC)
[    0.010000] 0: 0
[    0.010000] 1: 0
[    0.010000] 2: 0
[    0.010000] 3: 0
[    0.010000] 4: 0
[    0.010000] 5: 0
[    0.010000] 6: 0
[    0.010000] 7: 0
[    0.010000] Self-IPI invocations:
[    0.010000] 0: 0
[    0.010000] 1: 0
[    0.010000] 2: 0
[    0.010000] 3: 0
[    0.010000] 4: 0
[    0.010000] 5: 0
[    0.010000] 6: 0
[    0.010000] 7: 0
[    0.010000] IPIQ[0]: head = 0x0, tail = 0x0, depth = 0
[    0.010000] IPIQ[1]: head = 0x0, tail = 0x0, depth = 0
[    0.010000] IPIQ[2]: head = 0x0, tail = 0x0, depth = 0
[    0.010000] IPIQ[3]: head = 0x0, tail = 0x0, depth = 0
[    0.010000] IPIQ[4]: head = 0x0, tail = 0x0, depth = 0
[    0.010000] IPIQ[5]: head = 0x0, tail = 0x0, depth = 0
[    0.010000] IPIQ[6]: head = 0x0, tail = 0x0, depth = 0
[    0.010000] IPIQ[7]: head = 0x0, tail = 0x0, depth = 0
[    0.010000] 0 Recoveries of "stolen" FPU
[    0.010000] ===========================





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