Since commit 0f04cf8d ("drm/exynos:
fix wrong pipe calculation for crtc"), fimd_clear_channel() can be
called when is_drm_iommu_supported() returns true. In this case,
the kernel is going to be panicked because crtc is not set yet.

[    1.211156] [drm] Initialized drm 1.1.0 20060810
[    1.216785] Unable to handle kernel NULL pointer dereference at virtual address 00000350
[    1.223415] pgd = c0004000
[    1.226086] [00000350] *pgd=00000000
[    1.229649] Internal error: Oops: 5 [#1] PREEMPT SMP ARM
[    1.234940] Modules linked in:
[    1.237982] CPU: 2 PID: 1 Comm: swapper/0 Not tainted 4.0.0-rc1-00062-g7a7cc79-dirty #123
[    1.246136] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[    1.252214] task: ee8c8000 ti: ee8d0000 task.ti: ee8d0000
[    1.257606] PC is at fimd_wait_for_vblank+0x8/0xc8
[    1.262370] LR is at fimd_bind+0x138/0x1a8
[    1.266450] pc : [<c02fb63c>]    lr : [<c02fb834>]    psr: 20000113
[    1.266450] sp : ee8d1d28  ip : 00000000  fp : 00000000
[    1.277906] r10: 00000001  r9 : c09d693c  r8 : c0a2d6a8
[    1.283114] r7 : 00000034  r6 : 00000001  r5 : ee0bb400  r4 : ee244c10
[    1.289624] r3 : 00000000  r2 : 00000000  r1 : 00000001  r0 : 00000000
[    1.296135] Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
[    1.303426] Control: 10c5387d  Table: 4000404a  DAC: 00000015
[    1.309154] Process swapper/0 (pid: 1, stack limit = 0xee8d0210)
[    1.315143] Stack: (0xee8d1d28 to 0xee8d2000)
[    1.319486] 1d20:                   00000000 c0113d18 ee0bb400 ee0bb400 ee245c30 eebbe210
[    1.327645] 1d40: ee008a40 ee244c10 ee0bb400 00000001 00000034 c02fb834 00000000 c030a858
[    1.335804] 1d60: ee244a10 eeb60780 ee008a40 eeb60740 ee0bb400 c03030d0 00000000 00000000
[    1.343963] 1d80: ee244a10 ee0bb400 00000000 eeb60740 eeb60810 00000000 00000000 c02f6ba4
[    1.352123] 1da0: ee0bb400 00000000 00000000 c02e0500 ee244a00 c0a04a14 ee0bb400 c02e1de4
[    1.360282] 1dc0: 00000000 c030a858 00000002 eeb60820 eeb60820 00000002 eeb60780 c03033d4
[    1.368441] 1de0: c06e9cec 00000000 ee244a10 eeb60780 c0a056f8 c03035fc c0a04b24 c0a04b24
[    1.376600] 1e00: ee244a10 00000001 c0a049d0 c02f6d34 c0ad462c eeba0790 00000000 ee244a10
[    1.384759] 1e20: ffffffed c0a049d0 00000000 c03090b0 ee244a10 c0ad462c c0a2d840 c03077a0
[    1.392919] 1e40: eeb5e880 c024b738 000008db ee244a10 c0a049d0 ee244a44 00000000 c09e71d8
[    1.401078] 1e60: 000000c6 c0307a6c c0a049d0 00000000 c03079e0 c0305ea8 ee826e5c ee1dc7b4
[    1.409237] 1e80: c0a049d0 eeb5e880 c0a058a8 c0306e2c c0896204 c0a049d0 c06e9d10 c0a049d0
[    1.417396] 1ea0: c06e9d10 c0ad4600 00000000 c0308360 00000000 00000003 c06e9d10 c02f6e14
[    1.425555] 1ec0: 00000000 c0896204 ffffffff 00000000 00000000 00000000 00000000 00000000
[    1.433714] 1ee0: 00000000 00000000 c02f6d5c c02f6d5c 00000000 eeb5d740 c09e71d8 c0008a30
[    1.441874] 1f00: ef7fca5e 00000000 00000000 00000066 00000000 ee8d1f28 c003ff1c c02514e8
[    1.450033] 1f20: 60000113 ffffffff c093906c ef7fca5e 000000c6 c004018c 00000000 c093906c
[    1.458192] 1f40: c08a9690 c093840c 00000006 00000006 c09eb2ac c09c0d74 00000006 c09c0d54
[    1.466351] 1f60: c0a3d680 c09745a0 c09d693c 000000c6 00000000 c0974db4 00000006 00000006
[    1.474510] 1f80: c09745a0 ffffffff 00000000 c0692e00 00000000 00000000 00000000 00000000
[    1.482669] 1fa0: 00000000 c0692e08 00000000 c000f040 00000000 00000000 00000000 00000000
[    1.490828] 1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[    1.498988] 1fe0: 00000000 00000000 00000000 00000000 00000013 00000000 ffffffff ffffffff
[    1.507159] [<c02fb63c>] (fimd_wait_for_vblank) from [<c02fb834>] (fimd_bind+0x138/0x1a8)
[    1.515313] [<c02fb834>] (fimd_bind) from [<c03030d0>] (component_bind_all+0xc4/0x20c)
[    1.523209] [<c03030d0>] (component_bind_all) from [<c02f6ba4>] (exynos_drm_load+0xa0/0x140)
[    1.531632] [<c02f6ba4>] (exynos_drm_load) from [<c02e0500>] (drm_dev_register+0xa0/0xf4)
[    1.539788] [<c02e0500>] (drm_dev_register) from [<c02e1de4>] (drm_platform_init+0x44/0xcc)
[    1.548121] [<c02e1de4>] (drm_platform_init) from [<c03033d4>] (try_to_bring_up_master.part.1+0xc8/0x104)
[    1.557668] [<c03033d4>] (try_to_bring_up_master.part.1) from [<c03035fc>] (component_master_add_with_match+0xd0/0x118)
[    1.568431] [<c03035fc>] (component_master_add_with_match) from [<c02f6d34>] (exynos_drm_platform_probe+0xf0/0x118)
[    1.578847] [<c02f6d34>] (exynos_drm_platform_probe) from [<c03090b0>] (platform_drv_probe+0x48/0x98)
[    1.588052] [<c03090b0>] (platform_drv_probe) from [<c03077a0>] (driver_probe_device+0x140/0x380)
[    1.596902] [<c03077a0>] (driver_probe_device) from [<c0307a6c>] (__driver_attach+0x8c/0x90)
[    1.605321] [<c0307a6c>] (__driver_attach) from [<c0305ea8>] (bus_for_each_dev+0x54/0x88)
[    1.613480] [<c0305ea8>] (bus_for_each_dev) from [<c0306e2c>] (bus_add_driver+0xec/0x200)
[    1.621640] [<c0306e2c>] (bus_add_driver) from [<c0308360>] (driver_register+0x78/0xf4)
[    1.629625] [<c0308360>] (driver_register) from [<c02f6e14>] (exynos_drm_init+0xb8/0x11c)
[    1.637785] [<c02f6e14>] (exynos_drm_init) from [<c0008a30>] (do_one_initcall+0xac/0x1ec)
[    1.645950] [<c0008a30>] (do_one_initcall) from [<c0974db4>] (kernel_init_freeable+0x194/0x268)
[    1.654626] [<c0974db4>] (kernel_init_freeable) from [<c0692e08>] (kernel_init+0x8/0xe4)
[    1.662699] [<c0692e08>] (kernel_init) from [<c000f040>] (ret_from_fork+0x14/0x34)
[    1.670246] Code: eaffffd5 c09df884 e92d40f0 e24dd01c (e5905350)
[    1.676408] ---[ end trace 804468492f306a6f ]---
[    1.680948] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
[    1.680948]
[    1.690035] CPU1: stopping
[    1.692727] CPU: 1 PID: 0 Comm: swapper/1 Tainted: G      D         4.0.0-rc1-00062-g7a7cc79-dirty #123
[    1.702097] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[    1.708192] [<c0016c84>] (unwind_backtrace) from [<c00129bc>] (show_stack+0x10/0x14)
[    1.715908] [<c00129bc>] (show_stack) from [<c0696f58>] (dump_stack+0x78/0xc8)
[    1.723108] [<c0696f58>] (dump_stack) from [<c0015020>] (handle_IPI+0x16c/0x2b4)
[    1.730485] [<c0015020>] (handle_IPI) from [<c00086bc>] (gic_handle_irq+0x64/0x6c)
[    1.738036] [<c00086bc>] (gic_handle_irq) from [<c00134c0>] (__irq_svc+0x40/0x74)
[    1.745498] Exception stack(0xee8fdf98 to 0xee8fdfe0)
[    1.750533] df80:                                                       00000000 00000000
[    1.758695] dfa0: ee8fdfe8 c0021780 c09df938 00000015 10c0387d c0a3d988 4000406a c09df8d4
[    1.766853] dfc0: c0a27a74 c09df940 01000000 ee8fdfe0 c00101c0 c00101c4 60000113 ffffffff
[    1.775015] [<c00134c0>] (__irq_svc) from [<c00101c4>] (arch_cpu_idle+0x30/0x3c)
[    1.782397] [<c00101c4>] (arch_cpu_idle) from [<c005e804>] (cpu_startup_entry+0x180/0x324)
[    1.790639] [<c005e804>] (cpu_startup_entry) from [<40008764>] (0x40008764)
[    1.797579] CPU0: stopping
[    1.800272] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G      D         4.0.0-rc1-00062-g7a7cc79-dirty #123
[    1.809642] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[    1.815730] [<c0016c84>] (unwind_backtrace) from [<c00129bc>] (show_stack+0x10/0x14)
[    1.823450] [<c00129bc>] (show_stack) from [<c0696f58>] (dump_stack+0x78/0xc8)
[    1.830653] [<c0696f58>] (dump_stack) from [<c0015020>] (handle_IPI+0x16c/0x2b4)
[    1.838030] [<c0015020>] (handle_IPI) from [<c00086bc>] (gic_handle_irq+0x64/0x6c)
[    1.845581] [<c00086bc>] (gic_handle_irq) from [<c00134c0>] (__irq_svc+0x40/0x74)
[    1.853043] Exception stack(0xc09ddf60 to 0xc09ddfa8)
[    1.858081] df60: 00000000 00000000 c09ddfb0 c0021780 c09df938 00000001 ffffffff c0a3d680
[    1.866239] df80: c09c0dec c09df8d4 c0a27a74 c09df940 01000000 c09ddfa8 c00101c0 c00101c4
[    1.874396] dfa0: 60000113 ffffffff
[    1.877872] [<c00134c0>] (__irq_svc) from [<c00101c4>] (arch_cpu_idle+0x30/0x3c)
[    1.885251] [<c00101c4>] (arch_cpu_idle) from [<c005e804>] (cpu_startup_entry+0x180/0x324)
[    1.893499] [<c005e804>] (cpu_startup_entry) from [<c0974bc8>] (start_kernel+0x324/0x37c)
[    1.901655] [<c0974bc8>] (start_kernel) from [<40008074>] (0x40008074)
[    1.908161] CPU3: stopping
[    1.910855] CPU: 3 PID: 0 Comm: swapper/3 Tainted: G      D         4.0.0-rc1-00062-g7a7cc79-dirty #123
[    1.920225] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[    1.926313] [<c0016c84>] (unwind_backtrace) from [<c00129bc>] (show_stack+0x10/0x14)
[    1.934034] [<c00129bc>] (show_stack) from [<c0696f58>] (dump_stack+0x78/0xc8)
[    1.941237] [<c0696f58>] (dump_stack) from [<c0015020>] (handle_IPI+0x16c/0x2b4)
[    1.948613] [<c0015020>] (handle_IPI) from [<c00086bc>] (gic_handle_irq+0x64/0x6c)
[    1.956165] [<c00086bc>] (gic_handle_irq) from [<c00134c0>] (__irq_svc+0x40/0x74)
[    1.963626] Exception stack(0xee901f98 to 0xee901fe0)
[    1.968661] 1f80:                                                       00000000 00000000
[    1.976823] 1fa0: ee901fe8 c0021780 c09df938 00000015 10c0387d c0a3d988 4000406a c09df8d4
[    1.984982] 1fc0: c0a27a74 c09df940 01000000 ee901fe0 c00101c0 c00101c4 60000113 ffffffff
[    1.993143] [<c00134c0>] (__irq_svc) from [<c00101c4>] (arch_cpu_idle+0x30/0x3c)
[    2.000522] [<c00101c4>] (arch_cpu_idle) from [<c005e804>] (cpu_startup_entry+0x180/0x324)
[    2.008765] [<c005e804>] (cpu_startup_entry) from [<40008764>] (0x40008764)
[    2.015710] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
Signed-off-by: Hyungwon Hwang <human.hwang@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>