Re: [PATCH v3 1/2] dt-bindings: arm: xen: document Xen iommu device

[Oleksii Moisieiev <Oleksii_Moisieiev@xxxxxxxx>]

Hi Stefano,

 > The tiny "xen,iommu-el2-v1" driver could be backported to the stable
 > trees, I would imagine. Otherwise, do you have another suggestion?

There is stub IOMMU driver already merged to the Linux Kernel:
Commit 1ca55d50e50c74747a7b8846dac306fbe5ac4cf5 ("xen/grant-dma-iommu: 
Introduce stub IOMMU driver" added by Oleksandr Tyshchenko.

I was able to use it as an empty IOMMU driver on my test setup:
Made the following device-tree changes:

xen_iommu: xen-iommu {
	compatible = "xen,grant-dma";
	iommu-cells = <0>;
};

i2c@e60b0000 {
	iommus = <&xen_iommu 0x0>;
};

Maybe this driver can be used to solve the deferred problem with some 
modifications?
What is your opinion?

Best regards,
Oleksii.