Re: Kmod driver at iicbus. attach() and config_intrhook(9)

Thanks for your answers, especially for "...controllers use interrupts 
to get notified about...".
It helped to understand.

Yes, I need it as I check on attach() if the device connected.
Everything was fine while I was loading the driver into an already 
running system,
but as soon as I loaded the driver at boot time, I saw that its sysctl 
variables was
only half filled (no result nor calculated values).
config_intrhook_oneshot() solved this issue.

Thanks once more

Oleksandr Tymoshenko писал 2020-08-19 11:24:
> Andriy Gapon ([email protected]) wrote:
>> On 18/08/2020 22:05, Alexander Mishin wrote:
>> > Hi
>> > ....
>> > But I see that some other devices (from /usr/src/sys/dev) uses CONFIG_INTRHOOK(9)
>> > on attach() for initialize themselfs.
>> > I wonder if I need this too?...
>> 
>> This is usually needed when a driver needs to talk to its device while
>> attaching.  E.g., to set some initial configuration or to confirm 
>> device's
>> identity, etc.
> 
> To extend Andriy's explanation a bit: all these operations may perform
> I2C transfers and most I2C controllers use interrupts to get notified
> about tranfer status change (finished, error, etc...). There is no
> guarantee that when driver's attach method is called interrupts are
> globally enabled. What would happen in this case is: I2C controller
> is going to initiate I2C operation and wait for an interrupt that's
> never going to be delivered. CONFIG_INTRHOOK is a solution for this
> problem, if your attach method requires interrupts - just split it
> in two parts and postpone running interrupt-dependent part until after
> interrupts are globally enabled.
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