On 10/29/2013 01:51 PM, Sylwester Nawrocki wrote:

clk_unregister() is currently not implemented and it is required when
a clock provider module needs to be unloaded.

Normally the clock supplier module is prevented to be unloaded by
taking reference on the module in clk_get().

For cases when the clock supplier module deinitializes despite the
consumers of its clocks holding a reference on the module, e.g. when
the driver is unbound through "unbind" sysfs attribute, there are
empty clock ops added. These ops are assigned temporarily to struct
clk and used until all consumers release the clock, to avoid invoking
callbacks from the module which just got removed.

This patch is now in Mike's clk-next and hence next-20131031, and causes
both a WARN and an OOPS when booting the Tegra Dalmore board. (See log
below)

If I do the following to fix some other issues:

1) Apply:
http://www.spinics.net/lists/arm-kernel/msg283619.html
clk: fix boot panic with non-dev-associated clocks

2) Merge some Tegra-specific bug-fixes:
https://lkml.org/lkml/2013/10/29/771
Re: pull request for Tegra clock rework and Tegra124 clock support

... then revert this patch a336ed7 "clk: Implement clk_unregister()",
everything works again.

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: CPU: 0 PID: 0 at include/linux/kref.h:47 __clk_get+0x6c/0x84()
[    0.000000] Modules linked in:
[    0.000000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.12.0-rc3-00069-g850d089 #172
[    0.000000] [<c00158f0>] (unwind_backtrace+0x0/0xf8) from [<c00117a8>] (show_stack+0x10/0x14)
[    0.000000] [<c00117a8>] (show_stack+0x10/0x14) from [<c053b0b4>] (dump_stack+0x80/0xc4)
[    0.000000] [<c053b0b4>] (dump_stack+0x80/0xc4) from [<c00251f4>] (warn_slowpath_common+0x64/0x88)
[    0.000000] [<c00251f4>] (warn_slowpath_common+0x64/0x88) from [<c0025234>] (warn_slowpath_null+0x1c/0x24)
[    0.000000] [<c0025234>] (warn_slowpath_null+0x1c/0x24) from [<c03a3f98>] (__clk_get+0x6c/0x84)
[    0.000000] [<c03a3f98>] (__clk_get+0x6c/0x84) from [<c03a17e0>] (of_clk_get+0x5c/0x74)
[    0.000000] [<c03a17e0>] (of_clk_get+0x5c/0x74) from [<c03a1830>] (of_clk_get_by_name+0x38/0xb4)
[    0.000000] [<c03a1830>] (of_clk_get_by_name+0x38/0xb4) from [<c073e114>] (tegra_pmc_init+0x70/0x298)
[    0.000000] [<c073e114>] (tegra_pmc_init+0x70/0x298) from [<c073de68>] (tegra_dt_init_irq+0x10/0x20)
[    0.000000] [<c073de68>] (tegra_dt_init_irq+0x10/0x20) from [<c0739384>] (init_IRQ+0x24/0x2c)
[    0.000000] [<c0739384>] (init_IRQ+0x24/0x2c) from [<c0737910>] (start_kernel+0x1a0/0x30c)
[    0.000000] [<c0737910>] (start_kernel+0x1a0/0x30c) from [<80008074>] (0x80008074)
[    0.000000] ---[ end trace 1b75b31a2719ed1c ]---

...

[   14.674455] Unable to handle kernel paging request at virtual address 6b6b6cc3
[   14.681719] pgd = c0004000
[   14.684517] [6b6b6cc3] *pgd=00000000
[   14.688166] Internal error: Oops: 5 [#1] PREEMPT SMP ARM
[   14.693507] Modules linked in:
[   14.696640] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G        W    3.12.0-rc3-00069-g850d089 #172
[   14.705385] task: ee07ea40 ti: ee098000 task.ti: ee098000
[   14.710837] PC is at module_put+0x28/0x78
[   14.714916] LR is at tegra_ehci_probe+0xac/0x3b8
[   14.719575] pc : [<c0077b18>]    lr : [<c031d910>]    psr: 20000113
[   14.719575] sp : ee099e60  ip : ee018740  fp : 00000000
[   14.731092] r10: fffffdfb  r9 : ee098000  r8 : fffffdfb
[   14.736350] r7 : c058ad18  r6 : ee112410  r5 : ee0186c0  r4 : ee098000
[   14.742909] r3 : 00000001  r2 : 00000001  r1 : 000004d0  r0 : 6b6b6b6b
[   14.749473] Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
[   14.756824] Control: 10c5387d  Table: 8000406a  DAC: 00000015
[   14.762601] Process swapper/0 (pid: 1, stack limit = 0xee098240)
[   14.768640] Stack: (0xee099e60 to 0xee09a000)
[   14.773045] 9e60: ee365800 c031d910 c031d864 c0808e58 ee112410 00000000 c079e924 c074fe3c
[   14.781273] 9e80: c07374e0 c02a225c c02a2244 c02a1108 00000000 ee112410 c079e924 ee112444
[   14.789498] 9ea0: 00000000 c02a12b0 00000000 c079e924 c02a1224 c029f73c ee0880e0 ee1135f4
[   14.797722] 9ec0: c079e924 ee37fb40 c0798bd0 c02a07dc c06a645c c079e924 c079e924 00000006
[   14.805946] 9ee0: c0760ab8 c07c0900 c074fe3c c02a18c8 c02a2284 c076d118 00000006 c00089d8
[   14.814170] 9f00: c07e60d8 ee133840 c0543d24 000000bf c07c0900 00000001 00000000 c0781dd8
[   14.822393] 9f20: 60000113 00000001 00000008 c182b1d2 c055e284 c003d620 ee099f64 c004741c
[   14.830617] 9f40: c06abae4 c070618c 00000006 00000006 c0781dc8 c076d118 00000006 c0760ab8
[   14.838841] 9f60: c07c0900 000000b9 c0760ac4 c07374e0 00000000 c0737b78 00000006 00000006
[   14.847064] 9f80: c07374e0 ffffffff 00000000 c0536aec 00000000 00000000 00000000 00000000
[   14.855288] 9fa0: 00000000 c0536af4 00000000 c000e678 00000000 00000000 00000000 00000000
[   14.863509] 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[   14.871732] 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000 ffffffff ffffffff
[   14.879994] [<c0077b18>] (module_put+0x28/0x78) from [<c031d910>] (tegra_ehci_probe+0xac/0x3b8)
[   14.888782] [<c031d910>] (tegra_ehci_probe+0xac/0x3b8) from [<c02a225c>] (platform_drv_probe+0x18/0x1c)
[   14.898247] [<c02a225c>] (platform_drv_probe+0x18/0x1c) from [<c02a1108>] (driver_probe_device+0x108/0x224)
[   14.908050] [<c02a1108>] (driver_probe_device+0x108/0x224) from [<c02a12b0>] (__driver_attach+0x8c/0x90)
[   14.917607] [<c02a12b0>] (__driver_attach+0x8c/0x90) from [<c029f73c>] (bus_for_each_dev+0x54/0x88)
[   14.926729] [<c029f73c>] (bus_for_each_dev+0x54/0x88) from [<c02a07dc>] (bus_add_driver+0xd4/0x258)
[   14.935837] [<c02a07dc>] (bus_add_driver+0xd4/0x258) from [<c02a18c8>] (driver_register+0x78/0xf4)
[   14.944862] [<c02a18c8>] (driver_register+0x78/0xf4) from [<c00089d8>] (do_one_initcall+0xe4/0x140)
[   14.953982] [<c00089d8>] (do_one_initcall+0xe4/0x140) from [<c0737b78>] (kernel_init_freeable+0xfc/0x1c4)
[   14.963624] [<c0737b78>] (kernel_init_freeable+0xfc/0x1c4) from [<c0536af4>] (kernel_init+0x8/0xe4)
[   14.972748] [<c0536af4>] (kernel_init+0x8/0xe4) from [<c000e678>] (ret_from_fork+0x14/0x3c)
[   14.981155] Code: e5943004 e2833001 e5843004 f57ff05a (e5903158) 
[   14.987438] ---[ end trace 1b75b31a2719ed1d ]---
[   14.992109] note: swapper/0[1] exited with preempt_count 1
[   14.997752] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
[   14.997752] 
[   15.006970] CPU2: stopping
[   15.009756] CPU: 2 PID: 0 Comm: swapper/2 Tainted: G      D W    3.12.0-rc3-00069-g850d089 #172
[   15.018572] [<c00158f0>] (unwind_backtrace+0x0/0xf8) from [<c00117a8>] (show_stack+0x10/0x14)
[   15.027180] [<c00117a8>] (show_stack+0x10/0x14) from [<c053b0b4>] (dump_stack+0x80/0xc4)
[   15.035341] [<c053b0b4>] (dump_stack+0x80/0xc4) from [<c00142e8>] (handle_IPI+0xfc/0x120)
[   15.043587] [<c00142e8>] (handle_IPI+0xfc/0x120) from [<c0008704>] (gic_handle_irq+0x54/0x5c)
[   15.052183] [<c0008704>] (gic_handle_irq+0x54/0x5c) from [<c00122a0>] (__irq_svc+0x40/0x70)
[   15.060573] Exception stack(0xee0b7fa0 to 0xee0b7fe8)
[   15.065671] 7fa0: ffffffed 010d0000 c077b968 00000000 ee0b6000 c07c0747 00000001 c07c0747
[   15.073900] 7fc0: c077a44c c077a3d4 c05430cc 00000000 00000001 ee0b7fe8 c000f1dc c000f1d4
[   15.082114] 7fe0: 60000113 ffffffff
[   15.085679] [<c00122a0>] (__irq_svc+0x40/0x70) from [<c000f1d4>] (arch_cpu_idle+0x28/0x38)
[   15.094019] [<c000f1d4>] (arch_cpu_idle+0x28/0x38) from [<c0061d58>] (cpu_startup_entry+0x60/0x134)
[   15.103127] [<c0061d58>] (cpu_startup_entry+0x60/0x134) from [<800087a4>] (0x800087a4)
[   15.111089] CPU3: stopping
[   15.113872] CPU: 3 PID: 0 Comm: swapper/3 Tainted: G      D W    3.12.0-rc3-00069-g850d089 #172
[   15.122680] [<c00158f0>] (unwind_backtrace+0x0/0xf8) from [<c00117a8>] (show_stack+0x10/0x14)
[   15.131284] [<c00117a8>] (show_stack+0x10/0x14) from [<c053b0b4>] (dump_stack+0x80/0xc4)
[   15.139441] [<c053b0b4>] (dump_stack+0x80/0xc4) from [<c00142e8>] (handle_IPI+0xfc/0x120)
[   15.147683] [<c00142e8>] (handle_IPI+0xfc/0x120) from [<c0008704>] (gic_handle_irq+0x54/0x5c)
[   15.156280] [<c0008704>] (gic_handle_irq+0x54/0x5c) from [<c00122a0>] (__irq_svc+0x40/0x70)
[   15.164669] Exception stack(0xee0b9fa0 to 0xee0b9fe8)
[   15.169768] 9fa0: ffffffed 010d8000 c077b968 00000000 ee0b8000 c07c0747 00000001 c07c0747
[   15.177994] 9fc0: c077a44c c077a3d4 c05430cc 00000000 00000001 ee0b9fe8 c000f1dc c000f1d4
[   15.186208] 9fe0: 60000113 ffffffff
[   15.189771] [<c00122a0>] (__irq_svc+0x40/0x70) from [<c000f1d4>] (arch_cpu_idle+0x28/0x38)
[   15.198108] [<c000f1d4>] (arch_cpu_idle+0x28/0x38) from [<c0061d58>] (cpu_startup_entry+0x60/0x134)
[   15.207215] [<c0061d58>] (cpu_startup_entry+0x60/0x134) from [<800087a4>] (0x800087a4)
[   15.215178] CPU0: stopping
[   15.217953] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G      D W    3.12.0-rc3-00069-g850d089 #172
[   15.226758] [<c00158f0>] (unwind_backtrace+0x0/0xf8) from [<c00117a8>] (show_stack+0x10/0x14)
[   15.235363] [<c00117a8>] (show_stack+0x10/0x14) from [<c053b0b4>] (dump_stack+0x80/0xc4)
[   15.243522] [<c053b0b4>] (dump_stack+0x80/0xc4) from [<c00142e8>] (handle_IPI+0xfc/0x120)
[   15.251765] [<c00142e8>] (handle_IPI+0xfc/0x120) from [<c0008704>] (gic_handle_irq+0x54/0x5c)
[   15.260363] [<c0008704>] (gic_handle_irq+0x54/0x5c) from [<c00122a0>] (__irq_svc+0x40/0x70)
[   15.268754] Exception stack(0xc0773f68 to 0xc0773fb0)
[   15.273851] 3f60:                   ffffffed 010c0000 c077b968 00000000 c0772000 c07c0747
[   15.282080] 3f80: 00000001 c07c0747 c077a44c c077a3d4 c05430cc 00000000 00000020 c0773fb0
[   15.290297] 3fa0: c000f1dc c000f1d4 60000113 ffffffff
[   15.295421] [<c00122a0>] (__irq_svc+0x40/0x70) from [<c000f1d4>] (arch_cpu_idle+0x28/0x38)
[   15.303757] [<c000f1d4>] (arch_cpu_idle+0x28/0x38) from [<c0061d58>] (cpu_startup_entry+0x60/0x134)
[   15.312874] [<c0061d58>] (cpu_startup_entry+0x60/0x134) from [<c0737a28>] (start_kernel+0x2b8/0x30c)
[   15.322069] [<c0737a28>] (start_kernel+0x2b8/0x30c) from [<80008074>] (0x80008074)