Revision bd8733738c5af6114dd15d340b3f8713e9b624c2 authored by Boris Brezillon on 08 February 2015, 18:23:42 UTC, committed by Linus Walleij on 18 March 2015, 01:01:36 UTC
The gpiochip_lock_as_irq call can fail and return an error,
while the irq_startup is not expected to fail (returns an
unsigned int which is not checked by irq core code).

irq_request/release_resources functions have been created
to address this problem.

Move gpiochip_lock/unlock_as_irq calls into
irq_request/release_resources functions to prevent using a
gpio as an irq if the gpiochip_lock_as_irq call failed.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
1 parent 549e783
Raw File
IRQ.txt
What is an IRQ?

An IRQ is an interrupt request from a device.
Currently they can come in over a pin, or over a packet.
Several devices may be connected to the same pin thus
sharing an IRQ.

An IRQ number is a kernel identifier used to talk about a hardware
interrupt source.  Typically this is an index into the global irq_desc
array, but except for what linux/interrupt.h implements the details
are architecture specific.

An IRQ number is an enumeration of the possible interrupt sources on a
machine.  Typically what is enumerated is the number of input pins on
all of the interrupt controller in the system.  In the case of ISA
what is enumerated are the 16 input pins on the two i8259 interrupt
controllers.

Architectures can assign additional meaning to the IRQ numbers, and
are encouraged to in the case  where there is any manual configuration
of the hardware involved.  The ISA IRQs are a classic example of
assigning this kind of additional meaning.
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