Re: linux 4.2-rc1 broken Nokia N900

Michael Welling
2015-07-13T17:04:14Z

On Mon, Jul 13, 2015 at 10:09:21AM +0200, Sebastian Reichel wrote:
> [+cc Michael Welling <mwelling@ieee.org>, author of all omap-spi patches between 4.1 and 4.2-rc1]
>
> Hi,
>
> On Sun, Jul 12, 2015 at 11:44:25PM -0700, Tony Lindgren wrote:
> > * Pali Rohár <pali.rohar@gmail.com> [150711 05:07]:
> > > Hello,
> > >
> > > now I tested 4.2-rc1 release on Nokia N900 and couple of drivers are
> > > broken and cause kernel oops...
> > >
> > > Basically wifi, touchscreen and rtc drivers not working...
> > >
> > > Here are some relevant snippets form dmesg:
> > >
> > > [ 13.933959] Unhandled fault: external abort on non-linefetch (0x1028) at 0xfa09802c
> > > [ 13.940490] pgd = cfb38000
> > > [ 13.946594] [fa09802c] *pgd=48011452(bad)
> > > [ 13.952758] Internal error: : 1028 [#1] PREEMPT ARM
> > > [ 13.958862] Modules linked in: tsc2005(+) omap_sham twl4030_wdt omap_wdt
> > > [ 13.965332] CPU: 0 PID: 183 Comm: modprobe Not tainted 4.2.0-rc1+ #363
> > > [ 13.971801] Hardware name: Nokia RX-51 board
> > > [ 13.978302] task: cf572300 ti: cb1f2000 task.ti: cb1f2000
> > > [ 13.984924] PC is at omap2_mcspi_set_cs+0x44/0x4c

Here is the disassembly of the omap2_mcspi_set_cs function from my compiler:
00000040 <omap2_mcspi_set_cs>:
40: e2803e25 add r3, r0, #592 ; 0x250
44: e5902258 ldr r2, [r0, #600] ; 0x258
48: e1d330b2 ldrh r3, [r3, #2]
4c: e3130004 tst r3, #4
50: 12211001 eorne r1, r1, #1
54: e3520000 cmp r2, #0
58: 012fff1e bxeq lr
5c: e5923018 ldr r3, [r2, #24]
60: e3510000 cmp r1, #0
64: 13c33601 bicne r3, r3, #1048576 ; 0x100000
68: 03833601 orreq r3, r3, #1048576 ; 0x100000
6c: e5823018 str r3, [r2, #24]
70: e5902258 ldr r2, [r0, #600] ; 0x258
74: e5922000 ldr r2, [r2]
78: e582302c str r3, [r2, #44] ; 0x2c
7c: e5903258 ldr r3, [r0, #600] ; 0x258
80: e5933000 ldr r3, [r3]
84: e593202c ldr r2, [r3, #44] ; 0x2c
88: e12fff1e bx lr

The omap2_mcspi_set_cs function is being called before the controller_state is
initialized in omap2_mcspi_setup.

That is why there is a conditional checking if controller_state is NULL.

Perhaps the controller_state is uninitialized but has garbage instead of NULL
causing the data abort.

Though that does not make much sense because a similar check in the setup function
did not cause a data abort in the past.

Not sure what is going wrong here.

Could you do a objdump with the compiler you are using?

> > > [ 13.991485] LR is at spi_set_cs+0x5c/0x60
> > > [ 13.997985] pc : [<c02bd3ac>] lr : [<c02baecc>] psr: 20000013
> > > [ 13.997985] sp : cb1f3dd0 ip : 00000001 fp : 00000004
> > > [ 14.011260] r10: cfce5be8 r9 : 00000fff r8 : c0654f98
> > > [ 14.017913] r7 : 00000000 r6 : 00000000 r5 : 00000000 r4 : 00000000
> > > [ 14.024505] r3 : 200103dc r2 : fa098000 r1 : 00000001 r0 : cf09bc00
> > > [ 14.031036] Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
> > > [ 14.037689] Control: 10c5387d Table: 8fb38019 DAC: 00000015
> > > [ 14.044403] Process modprobe (pid: 183, stack limit = 0xcb1f2210)
> > > [ 14.051300] Stack: (0xcb1f3dd0 to 0xcb1f4000)
> > > [ 14.058105] 3dc0: cf09bc00 c02bafa4 cf09bc00 cf09bc00
> > > [ 14.065277] 3de0: bf013444 bf01254c cf0e2230 cf0e2230 00000001 c0654f98 00000fff 00000fff
> > > [ 14.072570] 3e00: 00000008 00000002 00000118 00001f40 00000031 cf09bc00 ffffffed bf013444
> > > [ 14.080078] 3e20: 00000031 c0654f98 cb1f2000 00000000 00000000 c02bb5c0 cf09bc00 00000000
> > > [ 14.087738] 3e40: bf013454 c027a2f4 00000000 cf09bc00 bf013454 bf013454 00000000 c027a594
> > > [ 14.095367] 3e60: 00000000 cf09bc00 cf09bc34 c027a60c bf013454 cb1f3e80 c027a5ac c0278ec8
> > > [ 14.102935] 3e80: cf972c4c cf09d630 bf013454 bf013454 cbb55300 c06848d8 00000000 c0279c84
> > > [ 14.110473] 3ea0: bf01327c bf01327d 00000000 bf013454 cb889180 00000000 c0654f98 c027b0c8
> > > [ 14.117980] 3ec0: 00000000 bf015000 cb889180 c00095b0 0040003e cfe6a080 0040003f 00000000
> > > [ 14.125457] 3ee0: 00080000 cfcf9000 cb1f2000 60000013 0040003e cbf1bbc0 00000000 00000001
> > > [ 14.132843] 3f00: bf0134cc cb1f2000 bf0134c0 cb1f3f58 00000000 c04352d0 cf801f00 000000d0
> > > [ 14.140136] 3f20: bf0134c0 bf0134c0 0000416c cb889040 00000080 c000ebe4 cb1f2000 c0089f68
> > > [ 14.147308] 3f40: bf0134c0 cbf1bc00 001a9193 0000416c 001f8d20 c008ab30 d0b10000 0000416c
> > > [ 14.154571] 3f60: d0b1267c d0b1252b d0b13514 000016c0 00001ad0 00000000 00000000 00000000
> > > [ 14.161865] 3f80: 0000001f 00000020 00000017 00000014 00000012 00000000 00201208 00000000
> > > [ 14.169097] 3fa0: 00000000 c000ea60 00201208 00000000 001f8d20 0000416c 001a9193 00000000
> > > [ 14.176177] 3fc0: 00201208 00000000 00000000 00000080 00208c20 001a9193 bee09e98 00000000
> > > [ 14.183197] 3fe0: b6f742b4 bee09ae4 000153f0 000093e4 60000010 001f8d20 72757463 69665f65
> > > [ 14.190277] [<c02bd3ac>] (omap2_mcspi_set_cs) from [<c02baecc>] (spi_set_cs+0x5c/0x60)
> > > [ 14.197479] [<c02baecc>] (spi_set_cs) from [<c02bafa4>] (spi_setup+0xd4/0x10c)
> > > [ 14.204833] [<c02bafa4>] (spi_setup) from [<bf01254c>] (tsc2005_probe+0x104/0x484 [tsc2005])
> > > [ 14.212249] [<bf01254c>] (tsc2005_probe [tsc2005]) from [<c02bb5c0>] (spi_drv_probe+0x50/0x6c)
> > > [ 14.219818] [<c02bb5c0>] (spi_drv_probe) from [<c027a2f4>] (really_probe+0xd4/0x230)
> > > [ 14.227478] [<c027a2f4>] (really_probe) from [<c027a594>] (driver_probe_device+0x30/0x48)
> > > [ 14.235290] [<c027a594>] (driver_probe_device) from [<c027a60c>] (__driver_attach+0x60/0x84)
> > > [ 14.243286] [<c027a60c>] (__driver_attach) from [<c0278ec8>] (bus_for_each_dev+0x50/0x84)
> > > [ 14.251281] [<c0278ec8>] (bus_for_each_dev) from [<c0279c84>] (bus_add_driver+0xcc/0x1e0)
> > > [ 14.259246] [<c0279c84>] (bus_add_driver) from [<c027b0c8>] (driver_register+0x9c/0xe0)
> > > [ 14.267272] [<c027b0c8>] (driver_register) from [<c00095b0>] (do_one_initcall+0x100/0x1b0)
> > > [ 14.275421] [<c00095b0>] (do_one_initcall) from [<c0089f68>] (do_init_module+0x58/0x1bc)
> > > [ 14.283477] [<c0089f68>] (do_init_module) from [<c008ab30>] (SyS_init_module+0x54/0x64)
> > > [ 14.291412] [<c008ab30>] (SyS_init_module) from [<c000ea60>] (ret_fast_syscall+0x0/0x3c)
> > > [ 14.299407] Code: e5823018 e5902188 e5922000 e582302c (e592302c)
> > > [ 14.307403] ---[ end trace d21553dcaefcb5ac ]---
> >
> > That seems to be a regression with the SPI driver. Care to git bisect it?
> > It's probably one of the following commits:
> >
> > $ git log --pretty=oneline v4.1..v4.2-rc2 drivers/spi/spi-omap2-mcspi.c
> >
> > Looks like just modprobe tsc2005 is enough to reproduce it.
>
> mh omap2_mcspi_set_cs has been introduced in this range
> (ddcad7e9068) and from the commit message it seems to be
> a fix for the first commit (b28cb9414d) in this range.
>
> Just looking at the commit log, I sugest starting with testing if
> ddcad7e9068 is affected and if b28cb9414d~1 is not affected.
>
> -- Sebastian