Re: [PATCH v2] of/iommu: support multiple iommu-map entries per input ID

[Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx>]

On Sun, Mar 15, 2026 at 10:37:43PM +0530, Vijayanand Jitta wrote:
> When multiple mappings are present for an input ID, linux matches
> just the first one. There is a usecase [1] where all the mappings
> are to be maintained in parallel for an iommu-map entry of a same
> input id.
> 
> Add a next_offset iterator parameter to of_map_iommu_id() and
> refactor of_map_id() internals into a static helper to carry it.
> Update of_iommu_configure_dev_id() to loop over all matching
> entries to support this case. All other callers pass NULL and
> are unaffected.
> 
> [1] 
> https://lore.kernel.org/all/20250627-video_cb-v3-0-51e18c0ffbce@xxxxxxxxxxx/
> 
> Signed-off-by: Vijayanand Jitta <vijayanand.jitta@xxxxxxxxxxxxxxxx>
> ---
> On Qualcomm kaanapali, the VPU hardware has multiple internal blocks
> that generate different stream IDs for the same input ID. The device
> tree encodes them as separate iommu-map entries sharing the same input
> ID:

Vijayanand, even I would not understand what you mean here. What is the
"input ID". Please describe the issue _exactly_, which blocks, what do
they genrate and when.

> 
>   iommu-map = <0x100 &apps_smmu 0x1940 0x1>,
>               <0x100 &apps_smmu 0x1a20 0x1>, ...
> 
> This requires multiple iommu-map entries per device.
> of_iommu_configure_dev_id() currently stops at the first match,
> so only one stream ID gets registered with the IOMMU.
> 

-- 
With best wishes
Dmitry