Re: [PATCH 04/15] irqchip/gic: WARN if setting the interrupt type fails

[Thomas Gleixner]

On Thu, 17 Mar 2016, Jon Hunter wrote:

> Setting the interrupt type for private peripheral interrupts (PPIs) may
> not be supported by a given GIC because it is IMPLEMENTATION DEFINED
> whether this is allowed. There is no way to know if setting the type is
> supported for a given GIC and so the value written is read back to
> verify it matches the desired configuration. If it does not match then
> an error is return.
> 
> There are cases where the interrupt configuration read from firmware
> (such as a device-tree blob), has been incorrect and hence
> gic_configure_irq() has returned an error. This error has gone
> undetected because the error code returned was ignored but the interrupt
> still worked fine because the configuration for the interrupt could not
> be overwritten.
> 
> Given that this has done undetected and we should only fail to set the
> type for PPIs whose configuration cannot be changed anyway, don't return
> an error and simply WARN if this fails. This will allows us to fix up any
> places in the kernel where we should be checking the return status and
> maintain back compatibility with firmware images that may have incorrect
> interrupt configurations.

Though silently returning 0 is really the wrong thing to do. You can add the
warn, but why do you want to return success?

Thanks,

	tglx