request_irq Vs request_threaded_irq

[Ranbir n]

Hi All,

What is difference between the request_irq & request_threaded_irq  apart from arguments. 

Regards,

Ranbir 

[Ameet Gandhare]

HI Ranbir,

As of Linux kernel 4.5.x, the function request_irq is a wrapper
calling request_threaded_irq.
The request_threaded_irq allocates the interrupt resources and IRQ
handling. From this point onwards,
the interrupt handler may get invoked.
Regards,
Ameet

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[Rajagopal P]

This was one of the interview question in irq, that i faced recently (at one of the leading mobile chipmaker in hyd), so providing some more links :)

https://www.quora.com/What-is-the-advantage-of-new-request_threaded_irq-over-request_irq

https://lwn.net/Articles/302043/

http://lists.kernelnewbies.org/pipermail/kernelnewbies/2011-March/001118.html

http://www.programmershare.com/2740674/

-Regards,Rajgopal

[real time]

Hi Rajgopal , 

Like work is divided between top and bottom half , using request_threaded_irq , you can divide the top half in two part . first part will just acknowledge the interrupt and second part is a thread will do the rest to finish the interrupt handling . this way system will be able to handle interrupt faster to reduce the interrupt processing latency and it will also avoid the locking between the ISR and bottom half . read this .

https://lwn.net/Articles/302043/

come back for any question.

Regards,