Re: What is meant by chained interrupt handlers, when to use them.

[Valmiki <valmikibow@gmail.com>]

Valmiki <valmikibow <at> gmail.com> writes:

> 
> I'm seeing that chained_irq_enter/exit functions are being used in 
cained 
> irq handlers. 
> 
> These chained_irq_enter/exit functions are doing ack, mask, unmask 
> functions from irq chip. 
> Already when an interrupt handler is being executed that IRQ line will 
be 
> disabled by linux, so what is the purpose of masking/unmasking them.
> 
> What is term chained referring to, does it mean reading interrupt 
status 
> register and check for bit set one after and another handle that 
> corresponding IRQ, so in a chain fashion.


When we use irq_set_chained_handler the irq line will not be disabled, 
unlike request_irq ? 
If that is the case calling chained_irq_enter which does mask/unmask to 
only current irq line, but i see in some pcie root port drivers after 
calling this they are handling all the available interrupts but only one 
is masked ? Is this method correct ?

> 
> Valmiki
> 
>