On 2012-11-27 21:15, Steve Sakoman wrote:

During my testing I think I uncovered another issue :-(

I set omapdss.def_disp=lcd43 on the kernel command line to see if the
behavior changed with the LCD as the default device.

What I encountered was a null pointer crash:

[    3.483062] fbcvt: 1024x768@60: CVT Name - .786M3-R
[    3.488250] Unable to handle kernel NULL pointer dereference at
virtual address 00000028
[    3.496765] pgd = c0004000
[    3.499603] [00000028] *pgd=00000000
[    3.503387] Internal error: Oops: 5 [#1] PREEMPT ARM
[    3.508605] Modules linked in:
[    3.511810] CPU: 0    Not tainted  (3.6.0 #1)
[    3.516357] PC is at dss_mgr_check_timings+0x4/0x30
[    3.521484] LR is at dpi_check_timings+0x18/0xb8
[    3.526336] pc : [<c025df70>]    lr : [<c0260dc0>]    psr: 40000013
[    3.526336] sp : dec2bd88  ip : 22222222  fp : def7e180
[    3.538330] r10: def951c0  r9 : def61000  r8 : de41b858
[    3.543823] r7 : dec2bdfc  r6 : c06c0a50  r5 : dec2be00  r4 : deea1cd4
[    3.550659] r3 : dec1ba40  r2 : dec2bdc8  r1 : dec2be00  r0 : 00000000
[    3.557495] Flags: nZcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM
Segment kernel
[    3.565155] Control: 10c5387d  Table: 80004019  DAC: 00000015
[    3.571166] Process swapper (pid: 1, stack limit = 0xdec2a2f0)
[    3.577270] Stack: (0xdec2bd88 to 0xdec2c000)
[    3.581848] bd80:                   dec1ba40 c0260dc0 ffffffff
deea1cd4 def7e180 c046a7d0
[    3.590423] bda0: 22222222 22222222 22222222 22222222 deea1cd4
c06c0a50 dec2be00 dec2bdfc
[    3.598968] bdc0: deea1cd4 c06c0a50 dec2be00 c026e738 c06c0a50
00000000 de41b800 c046749c
[    3.607513] bde0: 0000003d c0495788 00000018 00000000 00000010
def98640 dec00140 00000000
[    3.616088] be00: 03000400 0000dac0 00300020 00040050 0003000f
00000001 00000000 00000000
[    3.624664] be20: 00000001 00000000 00000000 c0459380 deea257c
c06c0d00 dec2be50 00000000
[    3.633209] be40: c025cc10 c029a98c 00000000 c029ae80 dec075d8
00000000 00000000 de41b800
[    3.641784] be60: c06c1200 c06c3098 c06c3090 de41b80c 00000002
00000001 de41b800 c0689470
[    3.650360] be80: def99148 def99148 dec2beb8 c01371c4 dec1ba40
00000000 def99148 decdf208
[    3.658935] bea0: def95240 c0137e24 00000000 c0054e18 00000000
00000003 decdf208 00000000
[    3.667510] bec0: c06e25dc c06c3098 c06e25dc c06e25dc c029c728
0000009e 00000000 c068920c
[    3.676055] bee0: 00000000 c029d830 c029d81c c029c514 c06e25dc
c06c3098 c06c3098 c06c30cc
[    3.684631] bf00: c06e25dc c029c790 00000000 dec2bf18 c06e25dc
c029aa9c dec077d8 decd9670
[    3.693176] bf20: c06e25dc c06e25dc c06e8868 def95240 00000000
c029bb2c c05a9b18 c05a9b18
[    3.701751] bf40: c06e25dc 00000001 c06a0c9c c0710300 0000009e
c029ccb4 00000000 c06e25c8
[    3.710296] bf60: 00000001 c06a0c9c c0710300 0000009e c068920c
c029daa4 00000007 c06967d8
[    3.718872] bf80: c06a0c9c c0689234 dec2a000 c0008654 c068920c
976c0d2e c06a0cc4 00000008
[    3.727447] bfa0: 00000007 c06967d8 c06a0c9c c0710300 0000009e
c0669160 c06967e0 c06698d8
[    3.735992] bfc0: 00000007 00000007 c0669160 00000013 00000000
00000000 00000000 c06697a0
[    3.744567] bfe0: c000eea8 00000013 00000000 00000000 00000000
c000eea8 fffffff7 dffefffe
[    3.753143] [<c025df70>] (dss_mgr_check_timings+0x4/0x30) from
[<c0260dc0>] (dpi_check_timings+0x18/0xb8)
[    3.763183] [<c0260dc0>] (dpi_check_timings+0x18/0xb8) from
[<c026e738>] (tfp410_check_timings+0x28/0x3c)
[    3.773223] [<c026e738>] (tfp410_check_timings+0x28/0x3c) from
[<c046749c>] (omapfb_parse_def_modes+0x338/0x3f4)
[    3.783905] [<c046749c>] (omapfb_parse_def_modes+0x338/0x3f4) from
[<c0689470>] (omapfb_probe+0x210/0x600)
[    3.794036] [<c0689470>] (omapfb_probe+0x210/0x600) from
[<c029d830>] (platform_drv_probe+0x14/0x18)
[    3.803619] [<c029d830>] (platform_drv_probe+0x14/0x18) from
[<c029c514>] (driver_probe_device+0x11c/0x330)
[    3.813812] [<c029c514>] (driver_probe_device+0x11c/0x330) from
[<c029c790>] (__driver_attach+0x68/0x8c)
[    3.823760] [<c029c790>] (__driver_attach+0x68/0x8c) from
[<c029aa9c>] (bus_for_each_dev+0x48/0x80)
[    3.833251] [<c029aa9c>] (bus_for_each_dev+0x48/0x80) from
[<c029bb2c>] (bus_add_driver+0xf0/0x248)
[    3.842742] [<c029bb2c>] (bus_add_driver+0xf0/0x248) from
[<c029ccb4>] (driver_register+0x9c/0x12c)
[    3.852203] [<c029ccb4>] (driver_register+0x9c/0x12c) from
[<c029daa4>] (platform_driver_probe+0x18/0x9c)
[    3.862243] [<c029daa4>] (platform_driver_probe+0x18/0x9c) from
[<c0689234>] (omapfb_init+0x28/0x54)
[    3.871826] [<c0689234>] (omapfb_init+0x28/0x54) from [<c0008654>]
(do_one_initcall+0x90/0x160)
[    3.880950] [<c0008654>] (do_one_initcall+0x90/0x160) from
[<c06698d8>] (kernel_init+0x138/0x1f8)
[    3.890228] [<c06698d8>] (kernel_init+0x138/0x1f8) from
[<c000eea8>] (kernel_thread_exit+0x0/0x8)
[    3.899566] Code: e3e00015 e8bd8010 c05d88aa e92d4008 (e5900028)
[    3.906097] ---[ end trace 38f657b10d460537 ]---

It seems that dss_mgr_check_timings is being called with a null dssdev->manager.

Other than the fact that there should be a null pointer check in the
code, it seems that this is a regression since it used to be possible
to switch the default display in this fashion.  Is this no longer
allowed?

It is allowed. Which kernel is that? I tried v3.7-rc4 and the current
omapdss master, both work for me with overo + lcd43 add on.

 Tomi