[PATCH v14 0/3] of: parsing of multi #{iommu,msi}-cells in maps

[Vijayanand Jitta]

On 5/7/2026 3:49 AM, Rob Herring wrote:
> On Fri, Apr 24, 2026 at 11:26:07AM +0530, Vijayanand Jitta wrote:
>> So far our parsing of {iommu,msi}-map properties has always blindly
>> assumed that the output specifiers will always have exactly 1 cell.
>> This typically does happen to be the case, but is not actually enforced
>> (and the PCI msi-map binding even explicitly states support for 0 or 1
>> cells) - as a result we've now ended up with dodgy DTs out in the field
>> which depend on this behaviour to map a 1-cell specifier for a 2-cell
>> provider, despite that being bogus per the bindings themselves.
>>
>> Since there is some potential use[1] in being able to map at least
>> single input IDs to multi-cell output specifiers (and properly support
>> 0-cell outputs as well), add support for properly parsing and using the
>> target nodes' #cells values, albeit with the unfortunate complication of
>> still having to work around expectations of the old behaviour too.
>> 							-- Robin.
>>
>> Unlike single #{}-cell, it is complex to establish a linear relation
>> between input 'id' and output specifier for multi-cell properties, thus
>> it is always expected that len never going to be > 1.
>>
>> These changes have been tested on QEMU for the arm64 architecture.
>>
>> Since, this would also need update in dt-schema, raised PR[2] for the
>> same.
> 
> Sashiko has some thoughts on the series:
> 
> https://sashiko.dev/#/patchset/20260424-parse_iommu_cells-v14-0-fd02f11b6c38%40oss.qualcomm.com
> 
> Rob

Thanks for the feedback, I have Posted v15 addressing comments from Sashiko.

v15: https://lore.kernel.org/all/20260520-parse_iommu_cells-v15-0-b5f99ad4e7e8@oss.qualcomm.com/

Thanks,
Vijay