Re: NULL pointer dereference when 'rmmod gpio_lynxpoint'

[Anatol Pomozov <anatol.pomozov@xxxxxxxxx>]

Hi

+Matt, the maintainer of Coreboot firmware that I use at this device.

On Sun, May 1, 2016 at 1:38 AM, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
> On Sun, May 1, 2016 at 2:33 AM, Anatol Pomozov <anatol.pomozov@xxxxxxxxx> wrote:
>
>> I am trying to 'rmmod gpio_lynxpoint' module at my Chromebox with Arch
>> 4.5.1 kernel and get this oops:
>>
>> [  118.801173] BUG: unable to handle kernel NULL pointer dereference
>> at 0000000000000078
>> [  118.801228] IP: [<ffffffff8105401f>] apic_ack_edge+0x2f/0x60
>
> Mathias Nyman is the maintainer of this driver. Interesting that
> a recent Chromebox is using Lynxpoint!
>
> Are you Cc:ing Laxman because you think the addition of
> devm_gpiochip_add_data() handling is causing it?

Yeah. I was looking at the history of recent changes in that file and
just CC a few people.

Starting from 4.2/4.3 kernel release I see numerous problems with this
driver. For example there are regular crashes at the boot time when
tries to load this driver https://goo.gl/photos/fGk2U6PgUFtxUk9w5    I
have to stick with Arch 4.1 kernel that does not have this problem.

> I think this looks much more related to the fact that we're removing
> an irqchip and it's not really working.
>
> GPIO drivers with backing irqchips are providing resources to other
> drivers, they are seldom really removeable.
>
> Maybe this driver should be made a bool?
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