[PATCH v15 02/15] irqdomain: Add IRQ_DOMAIN_FLAG_MSI_IMMUTABLE and irq_domain_is_msi_immutable()

[Marc Zyngier]

On Tue, 11 Feb 2025 19:21:55 +0000,
Frank Li <Frank.Li at nxp.com> wrote:
> 
> Add the flag IRQ_DOMAIN_FLAG_MSI_IMMUTABLE and the API function
> irq_domain_is_msi_immutable() to check if the MSI controller retains an
> immutable address/data pair during irq_set_affinity().
> 
> Ensure compatibility with MSI users like PCIe Endpoint Doorbell, which
> require the address/data pair to remain unchanged after setup. Use this
> function to verify if the MSI controller is immutable.

Why is that a requirement? Why should a driver even care?

	M.

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