Re: PC Engines APU/APU2 led driver

Alan Mizrahi
2017-09-16T14:00:29Z

On 2017-09-16 22:52, Pavel Machek wrote:
> Hi!
>
>>>> static void __exit apu_led_exit(void)
>>>> {
>>>> platform_device_unregister(apu_led->pdev);
>>>> platform_driver_unregister(&apu_led_driver);
>>>> }
>>>
>>> Normally, I'd expect _exit() to be 'reverse' of _init(). That is I'd
>>> expect reverese order there.
>>
>> That looked promising, but after inverting the order of the calls in
>> apu_led_exit(), the problem is still there but with a slightly different
>> backtrace:
>>
>> [ 11.320368] BUG: unable to handle kernel paging request at
>> ffffc900000b5618
>> [ 11.327702] IP: [<ffffffff811dd099>] ioread32+0x29/0x30
>> [ 11.333108] PGD 11a00e067 [ 11.335708] PUD 11a00f067
>> PMD 11a014067 [ 11.339807] PTE 0
>> [ 11.341783]
>> [ 11.343364] Oops: 0000 [#1] PREEMPT SMP
>> [ 11.347305] Modules linked in: arc4 ath10k_pci ath10k_core ath
>> mac80211 crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intele
>> [ 11.375310] CPU: 2 PID: 286 Comm: rmmod Not tainted 4.9.47 #37
>> [ 11.381342] Hardware name: PC Engines APU2/APU2, BIOS 4.0.7 02/28/2017
>> [ 11.388091] task: ffff880119af6540 task.stack: ffffc90000184000
>> [ 11.394168] RIP: 0010:[<ffffffff811dd099>] [<ffffffff811dd099>]
>> ioread32+0x29/0x30
>> [ 11.402044] RSP: 0018:ffffc90000187e40 EFLAGS: 00010292
>> [ 11.407567] RAX: 0000000000000000 RBX: ffff88011a1e4ac8 RCX:
>> 0000000000001a22
>> [ 11.414966] RDX: 0000000000000001 RSI: 0000000000000000 RDI:
>> ffffc900000b5618
>> [ 11.422416] RBP: 0000000000000000 R08: 00000000000195a0 R09:
>> ffff88011ed0e8c0
>> [ 11.429785] R10: ffffea0004686b80 R11: ffff88011a001c00 R12:
>> 0000000000000008
>> [ 11.437184] R13: ffff88011a1ae480 R14: ffff88011a1ae460 R15:
>> 00000000007c5010
>> [ 11.444535] FS: 00007f12f96ec700(0000) GS:ffff88011ed00000(0000)
>> knlGS:0000000000000000
>> [ 11.452906] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [ 11.458842] CR2: ffffc900000b5618 CR3: 0000000115dee000 CR4:
>> 00000000000406e0
>> [ 11.466308] Stack:
>> [ 11.468434] ffffffffa00d1023 ffff88011a1e4ac8 ffff88011a1e4ba0
>> ffffffffa005e076
>> [ 11.476255] ffffc90000187e78 ffff8801196ab810 ffffffff812923c0
>> ffff880119528dc0
>> [ 11.484073] ffff88011a1ae4a0 ffff8801196ab810 ffffffffa00d11e8
>> ffff8801196ab870
>> [ 11.491852] Call Trace:
>> [ 11.494427] [<ffffffffa00d1023>] ? apu2_led_brightness_set+0x23/0x58
>> [leds_apu]
>> [ 11.502178] [<ffffffffa005e076>] ? led_classdev_unregister+0x46/0xa0
>> [led_class]
>
> Hmm. can you put debug prints where in brightness_set() it fails?

That would be in ioread32().

> Is devm_() compatible with unregistering by hand?

I have no idea, but I based it on leds-mlxpld.c, and I assume it works
there.

Alan