[PATCH v14 0/3] Move backlight helper functions from tinydrm-helpers to linux/backlight

Meghana Madhyastha meghana.madhyastha at gmail.com
Mon Dec 11 13:17:11 UTC 2017


On Sat, Dec 09, 2017 at 03:09:28PM +0100, Noralf Trønnes wrote:
> 
> Den 21.10.2017 13.55, skrev Meghana Madhyastha:
> >Changes in v14:
> >- s/backlight_get/of_find_backlight/ in patch 2/3
> >- Change commit message in patch 3/3 from requiring to acquiring
> >
> >Meghana Madhyastha (3):
> >   drm/tinydrm: Move helper functions from tinydrm-helpers to backlight.h
> >   drm/tinydrm: Move tinydrm_of_find_backlight to backlight.c
> >   drm/tinydrm: Add devres versions of of_find_backlight
> 
> I tried the patchset and this is what I got:
> 
> [    8.057792] Unable to handle kernel paging request at virtual address
> fffffe6b
> [    8.069118] pgd = 93817cf7
> [    8.075704] [fffffe6b] *pgd=1bfd7861, *pte=00000000, *ppte=00000000
> [    8.086047] Internal error: Oops: 37 [#1] ARM
> [    8.094285] Modules linked in: mi0283qt(+) mipi_dbi tinydrm backlight
> bcm2835_rng rng_core
> [    8.110535] CPU: 0 PID: 121 Comm: systemd-udevd Not tainted 4.15.0-rc2+
> #2
> [    8.121531] Hardware name: BCM2835
> [    8.128964] task: 85dc6e21 task.stack: 4d8f2d19
> [    8.137482] PC is at kobject_put+0x18/0x1dc
> [    8.145556] LR is at put_device+0x24/0x28
> [    8.153312] pc : [<c076a1b4>]    lr : [<c048edb8>] psr: a0000013
> [    8.163321] sp : d6d33c18  ip : d6d33c40  fp : d6d33c3c
> [    8.172238] r10: c0496d38  r9 : 00000000  r8 : d6e46680
> [    8.181108] r7 : 00000004  r6 : d766bc00  r5 : d6d33c70  r4 : fffffe4b
> [    8.191237] r3 : bf0113b8  r2 : d766bd2c  r1 : d6e46710  r0 : fffffe4b
> [    8.201248] Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM Segment
> none
> [    8.211869] Control: 00c5387d  Table: 16d20008  DAC: 00000051
> [    8.221141] Process systemd-udevd (pid: 121, stack limit = 0xa0ab0c84)
> [    8.231264] Stack: (0xd6d33c18 to 0xd6d34000)
> [    8.239228] 3c00:                                                      
> bf011858 c049728c
> [    8.254539] 3c20: d7737010 d6e46700 d6d33c70 d766bc00 d6d33c4c d6d33c40
> c048edb8 c076a1a8
> [    8.270045] 3c40: d6d33c5c d6d33c50 bf0113dc c048eda0 d6d33c6c d6d33c60
> c0496fc4 bf0113c4
> [    8.285883] 3c60: d6d33ca4 d6d33c70 c04979f0 c0496fb4 d7737000 d6e46700
> d6d33c9c d766bc00
> [    8.301819] 3c80: 00000000 bf030100 c0d369dc c0d369e0 0000000e fffffdfb
> d6d33cb4 d6d33ca8
> [    8.317917] 3ca0: c0497ad0 c0497858 d6d33cec d6d33cb8 c0493efc c0497a94
> c057e738 c057d26c
> [    8.334043] 3cc0: d6d33cec d766bc00 d766bc34 bf030100 c0c4a5d8 00000001
> d6e46464 00000028
> [    8.350344] 3ce0: d6d33d0c d6d33cf0 c049414c c0493c4c 00000001 00000000
> bf030100 c04940b0
> [    8.367036] 3d00: d6d33d34 d6d33d10 c0492018 c04940bc d754f28c d76afbb0
> d6dca534 bf030100
> [    8.383997] 3d20: 00000000 d6dca500 d6d33d44 d6d33d38 c0493750 c0491fa8
> d6d33d6c d6d33d48
> [    8.401301] 3d40: c0493124 c0493734 bf02f4d6 d6d33d58 bf030100 bf033000
> c0c04048 00000000
> [    8.418938] 3d60: d6d33d84 d6d33d70 c0494954 c0493048 bf030140 bf033000
> d6d33d94 d6d33d88
> [    8.436692] 3d80: c04c8794 c04948b4 d6d33da4 d6d33d98 bf033020 c04c8748
> d6d33e1c d6d33da8
> [    8.454638] 3da0: c0101a30 bf03300c d6d33dcc d6d33db8 c01013f4 c03f7c64
> c0221690 60000013
> [    8.472918] 3dc0: d6d33e44 d6d33dd0 c010d04c c01013e0 d7401e40 014000c0
> 0000000c c0221770
> [    8.491185] 3de0: d6d33e1c d6d33df0 c0221770 c021e29c 00000001 fc36740d
> bf030140 00000001
> [    8.509455] 3e00: d6e46500 d6e46440 00000001 d6e46464 d6d33e44 d6d33e20
> c0178628 c0101978
> [    8.527727] 3e20: bf030140 d6e46440 d6d33e44 d6d33f40 00000001 bf030140
> d6d33f1c d6d33e48
> [    8.546000] 3e40: c0177810 c01785c8 bf03014c 00007fff bf030140 c0174ae8
> d6d33f38 d6d33eb8
> [    8.564264] 3e60: d6d33e9c b6d4f004 dcb059a4 c0c1619c bf030324 d6e46448
> bf030188 dcad6000
> [    8.582529] 3e80: 00000000 d6ca3e40 00000000 00000000 00000000 00000000
> 00000000 00000000
> [    8.600797] 3ea0: 00000000 00000000 00000000 00000000 6e72656b 00006c65
> 00000000 00000000
> [    8.619065] 3ec0: 00000000 00000000 00000000 00000000 00000000 00000000
> 00000000 00000000
> [    8.637319] 3ee0: 00000000 00000000 00000000 fc36740d 7fffffff 00000000
> b6d4f004 0000000d
> [    8.655582] 3f00: 0000017b c0108044 d6d32000 00000000 d6d33fa4 d6d33f20
> c0177f94 c0175d00
> [    8.673835] 3f20: 7fffffff 00000000 00000003 00000000 00000000 dcad6000
> 0002f9f4 00000000
> [    8.692093] 3f40: dcad6b80 dcad6000 0002f9f4 dcb05274 dcaf9e6a dcafa860
> 00003000 00003240
> [    8.710350] 3f60: 00000000 00000000 00000000 00001e34 0000002e 0000002f
> 00000019 00000000
> [    8.728612] 3f80: 00000013 00000000 00000000 1ef80900 00000000 00000000
> 00000000 d6d33fa8
> [    8.746870] 3fa0: c0107e60 c0177f04 1ef80900 00000000 0000000d b6d4f004
> 00000000 b6d4f928
> [    8.765132] 3fc0: 1ef80900 00000000 00000000 0000017b b6d4f004 00020000
> 00af6e18 00000000
> [    8.783394] 3fe0: bec95200 bec951f0 b6d4709c b6ea3c40 60000010 0000000d
> 00000000 00000000
> [    8.801685] [<c076a1b4>] (kobject_put) from [<c048edb8>]
> (put_device+0x24/0x28)
> [    8.814234] [<c048edb8>] (put_device) from [<bf0113dc>]
> (devm_backlight_put+0x24/0x28 [backlight])
> [    8.833323] [<bf0113dc>] (devm_backlight_put [backlight]) from
> [<c0496fc4>] (devm_action_release+0x1c/0x20)
> [    8.853182] [<c0496fc4>] (devm_action_release) from [<c04979f0>]
> (release_nodes+0x1a4/0x1cc)
> [    8.871702] [<c04979f0>] (release_nodes) from [<c0497ad0>]
> (devres_release_all+0x48/0x54)
> [    8.889956] [<c0497ad0>] (devres_release_all) from [<c0493efc>]
> (driver_probe_device+0x2bc/0x470)
> [    8.908937] [<c0493efc>] (driver_probe_device) from [<c049414c>]
> (__driver_attach+0x9c/0x100)
> [    8.927557] [<c049414c>] (__driver_attach) from [<c0492018>]
> (bus_for_each_dev+0x7c/0xa0)
> [    8.945822] [<c0492018>] (bus_for_each_dev) from [<c0493750>]
> (driver_attach+0x28/0x30)
> [    8.963916] [<c0493750>] (driver_attach) from [<c0493124>]
> (bus_add_driver+0xe8/0x240)
> [    8.981929] [<c0493124>] (bus_add_driver) from [<c0494954>]
> (driver_register+0xac/0xf0)
> [    9.000048] [<c0494954>] (driver_register) from [<c04c8794>]
> (__spi_register_driver+0x58/0x6c)
> [    9.018823] [<c04c8794>] (__spi_register_driver) from [<bf033020>]
> (mi0283qt_spi_driver_init+0x20/0x1000 [mi0283qt])
> [    9.039575] [<bf033020>] (mi0283qt_spi_driver_init [mi0283qt]) from
> [<c0101a30>] (do_one_initcall+0xc4/0x184)
> [    9.059727] [<c0101a30>] (do_one_initcall) from [<c0178628>]
> (do_init_module+0x6c/0x1fc)
> [    9.078036] [<c0178628>] (do_init_module) from [<c0177810>]
> (load_module+0x1b1c/0x2090)
> [    9.096248] [<c0177810>] (load_module) from [<c0177f94>]
> (SyS_finit_module+0x9c/0xcc)
> [    9.114284] [<c0177f94>] (SyS_finit_module) from [<c0107e60>]
> (ret_fast_syscall+0x0/0x54)
> [    9.132673] Code: e24cb004 e24dd00c e2504000 0a00005e (e5d43020)
> [    9.144181] ---[ end trace 149c05934b6a6dcc ]---

Is the reason possibly because we have omitted error checking on the
return value of backlight_enable function ? tinydrm_enable_backlight and
tinydrm_disable_baclight do this. 
Eg.
ret = backlight_update_status(backlight);
if (ret)
	DRM_ERROR("Failed to enable backlight %d\n", ret);

I'm not sure, just asking whether this could be a possible reason
for the above trace.

Regards,
Meghana

> Noralf.
> 
> >  drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 95 --------------------------
> >  drivers/gpu/drm/tinydrm/mi0283qt.c             |  3 +-
> >  drivers/gpu/drm/tinydrm/mipi-dbi.c             |  5 +-
> >  drivers/video/backlight/backlight.c            | 68 ++++++++++++++++++
> >  include/drm/tinydrm/tinydrm-helpers.h          |  4 --
> >  include/linux/backlight.h                      | 56 +++++++++++++++
> >  6 files changed, 129 insertions(+), 102 deletions(-)
> >
> 


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