Re: kernel 4.10-rcx iio helper question

[Daniel Baluta <daniel.baluta@gmail.com>]

On Tue, Jan 31, 2017 at 8:19 PM, Ken.Lin <ken.lin@advantech.com> wrote:
> Hi,
>
> I find the latest kernel introduces new iio sys attributes.
> https://patchwork.kernel.org/patch/9391771/
> https://patchwork.kernel.org/patch/9391259/
>
> Is there anyone has some ideas about how the new iio sys attribute - in_pressure_scale_available works?
> I'm not sure if it's the regression issue or it's just the usage issue or something when I tried to read in_pressure_scale_available attribute.
>
> # cat /sys/bus/iio/devices/iio\:device1/in_pressure_scale_available
> Segmentation fault
>
> [ 3785.077014] Unable to handle kernel NULL pointer dereference at virtual address 00000000
> [ 3785.085138] pgd = ecc3c000
> [ 3785.087929] [00000000] *pgd=87f91831
> [ 3785.091563] Internal error: Oops: 80000007 [#1] SMP ARM
> [ 3785.096806] Modules linked in:
> [ 3785.099892] CPU: 1 PID: 1051 Comm: cat Not tainted 4.10.0-rc5-00009-gffd8858-dirty #3
> [ 3785.107740] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
> [ 3785.114285] task: ed54ec00 task.stack: ee2bc000
> [ 3785.118834] PC is at 0x0
> [ 3785.121397] LR is at iio_read_channel_info_avail+0x40/0x280
> [ 3785.126992] pc : [<00000000>]    lr : [<c06fbc1c>]    psr: a0070013
> [ 3785.126992] sp : ee2bdda8  ip : 00000000  fp : ee2bddf4
> [ 3785.138490] r10: c0a53c74  r9 : ed79f000  r8 : ee8d1018
> [ 3785.143733] r7 : 00001000  r6 : 00000fff  r5 : ee8b9a00  r4 : ed79f000
> [ 3785.150276] r3 : ee2bddc4  r2 : ee2bddbc  r1 : c0a86dcc  r0 : ee8d1000
> [ 3785.156820] Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
> [ 3785.163971] Control: 10c5387d  Table: 3cc3c04a  DAC: 00000051
> [ 3785.169734] Process cat (pid: 1051, stack limit = 0xee2bc210)
> [ 3785.175497] Stack: (0xee2bdda8 to 0xee2be000)
> [ 3785.179880] dda0:                   ee2bddc0 00000002 c016d720 c016d394 ed54ec00 00000000
> [ 3785.188084] ddc0: 60070013 ed413780 00000001 edffd480 ee8b9a00 00000fff 00001000 ee8d1018
> [ 3785.196286] dde0: ed79f000 c0a53c74 ee2bde0c ee2bddf8 c0513c58 c06fbbe8 edffd480 edffd540
> [ 3785.204488] de00: ee2bde3c ee2bde10 c0293474 c0513c40 c02933e4 ee2bde60 00000001 ed413780
> [ 3785.212688] de20: 00000001 ed413780 00000000 edffd480 ee2bde4c ee2bde40 c0291d00 c02933f0
> [ 3785.220889] de40: ee2bde9c ee2bde50 c024679c c0291ce0 edffd4b0 b6e37000 00020000 ee2bdf78
> [ 3785.229089] de60: 00000000 00000000 ed54ec00 ed013200 00000817 c0a111fc edffd540 ed413780
> [ 3785.237289] de80: b6e37000 00020000 00020000 ee2bdf78 ee2bded4 ee2bdea0 c0292890 c0246604
> [ 3785.245491] dea0: c0117940 c016ba50 00000025 c0a111fc b6e37000 ed413780 ee2bdf78 00020000
> [ 3785.253691] dec0: ee2bc000 b6e37000 ee2bdf44 ee2bded8 c021d158 c0292770 c0117764 b6e36004
> [ 3785.261893] dee0: c0f0d7c4 ee2bdfb0 b6f89228 00021008 ee2bdfac ee2bdf00 c0101374 c0117770
> [ 3785.270093] df00: 00000000 00000000 ee2bc000 00000000 ee2bdf34 ee2bdf20 c016ba04 c0171080
> [ 3785.278292] df20: 00000000 00020000 ed413780 b6e37000 00000000 ee2bdf78 ee2bdf74 ee2bdf48
> [ 3785.286493] df40: c021e7a0 c021d130 c023e300 c023e280 ee2bdf74 00000000 00000000 ed413780
> [ 3785.294693] df60: ed413780 00020000 ee2bdfa4 ee2bdf78 c021e870 c021e71c 00000000 00000000
> [ 3785.302892] df80: 00020000 00020000 b6e37000 00000003 c0108084 00000000 00000000 ee2bdfa8
> [ 3785.311092] dfa0: c0107ee0 c021e838 00020000 00020000 00000003 b6e37000 00020000 0001a2b4
> [ 3785.319292] dfc0: 00020000 00020000 b6e37000 00000003 7fffe000 00000000 00000000 00020000
> [ 3785.327492] dfe0: 00000000 be98eb4c 0000c740 b6f1985c 60070010 00000003 00000000 00000000
> [ 3785.335679] Backtrace:
> [ 3785.338175] [<c06fbbdc>] (iio_read_channel_info_avail) from [<c0513c58>] (dev_attr_show+0x24/0x50)
> [ 3785.347162]  r10:c0a53c74 r9:ed79f000 r8:ee8d1018 r7:00001000 r6:00000fff r5:ee8b9a00
> [ 3785.355005]  r4:edffd480
> [ 3785.357571] [<c0513c34>] (dev_attr_show) from [<c0293474>] (sysfs_kf_seq_show+0x90/0x110)
> [ 3785.365764]  r5:edffd540 r4:edffd480
> [ 3785.369365] [<c02933e4>] (sysfs_kf_seq_show) from [<c0291d00>] (kernfs_seq_show+0x2c/0x30)
> [ 3785.377652]  r10:edffd480 r9:00000000 r8:ed413780 r7:00000001 r6:ed413780 r5:00000001
> [ 3785.385498]  r4:ee2bde60 r3:c02933e4
> [ 3785.389101] [<c0291cd4>] (kernfs_seq_show) from [<c024679c>] (seq_read+0x1a4/0x4e0)
> [ 3785.396780] [<c02465f8>] (seq_read) from [<c0292890>] (kernfs_fop_read+0x12c/0x1cc)
> [ 3785.404460]  r10:ee2bdf78 r9:00020000 r8:00020000 r7:b6e37000 r6:ed413780 r5:edffd540
> [ 3785.412303]  r4:c0a111fc
> [ 3785.414862] [<c0292764>] (kernfs_fop_read) from [<c021d158>] (__vfs_read+0x34/0x118)
> [ 3785.422627]  r10:b6e37000 r9:ee2bc000 r8:00020000 r7:ee2bdf78 r6:ed413780 r5:b6e37000
> [ 3785.430470]  r4:c0a111fc
> [ 3785.433029] [<c021d124>] (__vfs_read) from [<c021e7a0>] (vfs_read+0x90/0x11c)
> [ 3785.440185]  r8:ee2bdf78 r7:00000000 r6:b6e37000 r5:ed413780 r4:00020000
> [ 3785.446909] [<c021e710>] (vfs_read) from [<c021e870>] (SyS_read+0x44/0x90)
> [ 3785.453804]  r8:00020000 r7:ed413780 r6:ed413780 r5:00000000 r4:00000000
> [ 3785.460537] [<c021e82c>] (SyS_read) from [<c0107ee0>] (ret_fast_syscall+0x0/0x1c)
> [ 3785.468042]  r10:00000000 r8:c0108084 r7:00000003 r6:b6e37000 r5:00020000 r4:00020000
> [ 3785.476238] Code: bad PC value
> [ 3785.490358] ---[ end trace 9c4938ccd0389004 ]---


Hi Ken,

What sensor are you using?