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Date:   Sat, 10 Sep 2022 15:40:29 +0100
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From:   Marc Zyngier <maz@kernel.org>
To:     Frank Li <frank.li@nxp.com>
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Subject: Re: [EXT] Re: [PATCH v9 2/4] irqchip: Add IMX MU MSI controller driver
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On Fri, 09 Sep 2022 15:52:45 +0100,
Frank Li <frank.li@nxp.com> wrote:
> 
> > > +     select IRQ_DOMAIN
> > > +     select IRQ_DOMAIN_HIERARCHY
> > > +     select GENERIC_MSI_IRQ_DOMAIN
> > > +     help
> > > +       MU work as MSI controller to do general doorbell
> > 
> > I'm not sure this is that generic. It really is limited to CPU-to-CPU
> > interrupts.
> 
> [Frank Li] I think the only limitation is only 4 irq numbers. 
> The principle CPU to CPU irq is the same as MSI.

Not quite. Normal MSIs are device-to-CPU. CPU-to-CPU are normally
IPIs, and this one falls in the middle.

> What's  your preferred help description?

<quote>
	Provide a driver for the MU block used as a CPU-to-CPU MSI
	controller. This requires a specially crafted DT to make use
	of this driver.

	If unsure, say N.
</quote>

	M.

-- 
Without deviation from the norm, progress is not possible.