Re: [PATCH v5 04/13] iommu: of_iommu: Add support for "iommu-ranges" on a device node

[bod@kernel.org]

On 2026-09-26 12:04 +0530, Vikash Garodia wrote:
> Reserving an IOVA address using "iommu-addresses" requires it to be
> placed in the reserved-memory node. But when "iommu-addresses" is the
> only property being described and there is no backing "reg" (i.e. no
> actual reserved system memory), it does not really belong under
> /reserved-memory. A device IOVA range is specific to its own address
> space, and does not describe the system physical memory to make it
> qualify under reserved-memory. Given this, place "iommu-addresses"
> inside reserved-memory only when it is paired with a "reg", otherwise,
> define it within the device own node. It was discussed here:
> https://lore.kernel.org/all/662f7093-fb0a-4564-9ca0-98e03e68ba9a@kernel.org
> 
> Existing "iommu-addresses" property expects a phandle, which does
> not make sense when the property is defined within the device node.
> Introduce a new property, "iommu-ranges", to specify the device
> specific IOVA ranges when there is no backing "reg".
> 
> Suggested-by: Rob Herring <robh@kernel.org>
> Co-developed-by: Vishnu Reddy <busanna.reddy@oss.qualcomm.com>
> Signed-off-by: Vishnu Reddy <busanna.reddy@oss.qualcomm.com>
> Signed-off-by: Vikash Garodia <vikash.garodia@oss.qualcomm.com>

I think we need to get buy-in from the IOMMU people on this change before
we commit to bindings that may be affected by a rejection.

i.e. There's no point in absorbing potentially DOA bindings.
---
bod