[PATCH 02/16] drm/exynos: extract helper functions for probe

[Marek Szyprowski]

Hi

On 04.09.2020 11:04, Marek Szyprowski wrote:
> On 03.09.2020 18:57, Michael Tretter wrote:
>> As the driver shall be usable with drivers that use the component
>> framework and drivers that don't, split the common probing code into a
>> separate function that can be called from different locations.
>>
>> Signed-off-by: Michael Tretter <m.tretter at pengutronix.de>
>
> This is the first patch that causes the crash on Exynos boards:
>
> exynos4-fb 11c00000.fimd: Adding to iommu group 0
> OF: graph: no port node found in /soc/fimd at 11c00000
> [drm] Exynos DRM: using 11c00000.fimd device for DMA mapping operations
> exynos-drm exynos-drm: bound 11c00000.fimd (ops fimd_component_ops)
> OF: graph: no port node found in /soc/dsi at 11c80000
> 8<--- cut here ---
> Unable to handle kernel NULL pointer dereference at virtual address 
> 00000084
> pgd = (ptrval)
> [00000084] *pgd=00000000
> Internal error: Oops: 5 [#1] PREEMPT SMP ARM
> Modules linked in:
> CPU: 1 PID: 1 Comm: swapper/0 Not tainted 
> 5.9.0-rc2-next-20200824-00004-g680baccba1c2 #1591
> Hardware name: Samsung Exynos (Flattened Device Tree)
> PC is at drm_bridge_attach+0x18/0x164
> LR is at exynos_dsi_bind+0x88/0x9c
> pc : [<c0620524>]    lr : [<c0644df8>]    psr: 20000013
> ...
> Process swapper/0 (pid: 1, stack limit = 0x(ptrval))
> ...
> [<c0620524>] (drm_bridge_attach) from [<c0644df8>] 
> (exynos_dsi_bind+0x88/0x9c)
> [<c0644df8>] (exynos_dsi_bind) from [<c0661aec>] 
> (component_bind_all+0xfc/0x290)
> [<c0661aec>] (component_bind_all) from [<c06413d0>] 
> (exynos_drm_bind+0xe4/0x19c)
> [<c06413d0>] (exynos_drm_bind) from [<c0662060>] 
> (try_to_bring_up_master+0x1e4/0x2c4)
> [<c0662060>] (try_to_bring_up_master) from [<c06625a0>] 
> (component_master_add_with_match+0xd4/0x108)
> [<c06625a0>] (component_master_add_with_match) from [<c06410f8>] 
> (exynos_drm_platform_probe+0xe4/0x110)
> [<c06410f8>] (exynos_drm_platform_probe) from [<c066c788>] 
> (platform_drv_probe+0x6c/0xa4)
> [<c066c788>] (platform_drv_probe) from [<c0669cc4>] 
> (really_probe+0x200/0x4fc)
> [<c0669cc4>] (really_probe) from [<c066a188>] 
> (driver_probe_device+0x78/0x1fc)
> [<c066a188>] (driver_probe_device) from [<c066a570>] 
> (device_driver_attach+0x58/0x60)
> [<c066a570>] (device_driver_attach) from [<c066a654>] 
> (__driver_attach+0xdc/0x174)
> [<c066a654>] (__driver_attach) from [<c0667a4c>] 
> (bus_for_each_dev+0x68/0xb4)
> [<c0667a4c>] (bus_for_each_dev) from [<c0668d80>] 
> (bus_add_driver+0x158/0x214)
> [<c0668d80>] (bus_add_driver) from [<c066b538>] 
> (driver_register+0x78/0x110)
> [<c066b538>] (driver_register) from [<c06412b8>] 
> (exynos_drm_init+0xe4/0x118)
> [<c06412b8>] (exynos_drm_init) from [<c01023f4>] 
> (do_one_initcall+0x8c/0x424)
> [<c01023f4>] (do_one_initcall) from [<c10011a8>] 
> (kernel_init_freeable+0x190/0x1dc)
> [<c10011a8>] (kernel_init_freeable) from [<c0ae8ab4>] 
> (kernel_init+0x8/0x118)
> [<c0ae8ab4>] (kernel_init) from [<c0100114>] (ret_from_fork+0x14/0x20)
> Exception stack(0xef0dffb0 to 0xef0dfff8)
> ffa0:                                     00000000 00000000 00000000 
> 00000000
> ffc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 
> 00000000
> ffe0: 00000000 00000000 00000000 00000000 00000013 00000000
> Code: e92d4070 0a00002e e3520000 0a000044 (e592c06c)
> ---[ end trace 1c93b26d166070f6 ]---
> Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
> CPU0: stopping
> CPU: 0 PID: 0 Comm: swapper/0 Tainted: G      D 
> 5.9.0-rc2-next-20200824-00004-g680baccba1c2 #1591
> Hardware name: Samsung Exynos (Flattened Device Tree)
> [<c011160c>] (unwind_backtrace) from [<c010cfc0>] (show_stack+0x10/0x14)
> [<c010cfc0>] (show_stack) from [<c0533c3c>] (dump_stack+0xbc/0xe8)
> [<c0533c3c>] (dump_stack) from [<c01104e0>] (handle_IPI+0x3e0/0x428)
> [<c01104e0>] (handle_IPI) from [<c05511dc>] (gic_handle_irq+0x98/0x9c)
> [<c05511dc>] (gic_handle_irq) from [<c0100af0>] (__irq_svc+0x70/0xb0)
> Exception stack(0xc1101f08 to 0xc1101f50)
> 1f00:                   c01095d8 00000000 00000000 c1100000 c1108eec 
> c1108f30
> 1f20: 00000001 c107d068 c1108ec8 00000000 00000000 00000000 00005dc0 
> c1101f58
> 1f40: c01095d8 c01095dc 60000013 ffffffff
> [<c0100af0>] (__irq_svc) from [<c01095dc>] (arch_cpu_idle+0x24/0x44)
> [<c01095dc>] (arch_cpu_idle) from [<c01635dc>] (do_idle+0x1bc/0x2bc)
> [<c01635dc>] (do_idle) from [<c0163a90>] (cpu_startup_entry+0x18/0x1c)
> [<c0163a90>] (cpu_startup_entry) from [<c1000f88>] 
> (start_kernel+0x628/0x664)
> [<c1000f88>] (start_kernel) from [<00000000>] (0x0)
> ---[ end Kernel panic - not syncing: Attempted to kill init! 
> exitcode=0x0000000b ]---

# arm-linux-gnueabi-addr2line -a c0620524 -e vmlinux
0xc0620524
drivers/gpu/drm/drm_bridge.c:184 (discriminator 1)

what is:

184:    if (previous && (!previous->dev || previous->encoder != encoder))

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland