So far our parsing of {iommu,msi}-map properites 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.

[1] https://lore.kernel.org/all/20250627-video_cb-v3-0-51e18c0ffbce@quicinc.com/

V8:
  Removed mentions of of_map_args from commit message to match code.

  Link to V7:
  https://lore.kernel.org/all/20260210101157.2145113-1-vijayanand.jitta@oss.qualcomm.com/

V7:
  Removed of_map_id_args structure and replaced it with of_phandle_args as
  suggested by Dmitry.

  Link to V6:
  https://lore.kernel.org/all/20260121055400.937856-1-vijayanand.jitta@oss.qualcomm.com/

V6:
  Fixed build error reported by kernel test bot.

  Link to V5:
  https://lore.kernel.org/all/20260118181125.1436036-1-vijayanand.jitta@oss.qualcomm.com/

V5:
  Fixed Build Warnings.
  Raised PR for iommu-map dtschema:
  https://github.com/devicetree-org/dt-schema/pull/184

  Link to V4:
  https://lore.kernel.org/all/20251231114257.2382820-1-vijayanand.jitta@oss.qualcomm.com/

V4:
  1) Added Reviewed-by tag.
  2) Resolved warnings reported by kernel test bot, minor code
  reorganization.

  Link to V3:
  https://lore.kernel.org/all/20251221213602.2413124-1-vijayanand.jitta@oss.qualcomm.com/

V3:
  1) Added Reviewed-by tag.
  2) Updated of_map_id_args struct as a wrapper to of_phandle_args and
  added comment description as suggested by Rob Herring.

  Link to V2:
  https://lore.kernel.org/all/20251204095530.8627-1-vijayanand.jitta@oss.qualcomm.com/

V2:
  1) Incorporated the patches from Robin that does the clean implementation.
  2) Dropped the patches the were adding multi-map support from this series
  as suggested.

V1:
 https://lore.kernel.org/all/cover.1762235099.git.charan.kalla@oss.qualcomm.com/

RFC:
 https://lore.kernel.org/all/20250928171718.436440-1-charan.kalla@oss.qualcomm.com/#r

Charan Teja Kalla (1):
  of: factor arguments passed to of_map_id() into a struct

Robin Murphy (2):
  of: Add convenience wrappers for of_map_id()
  of: Respect #{iommu,msi}-cells in maps

 drivers/cdx/cdx_msi.c                    |   3 +-
 drivers/iommu/of_iommu.c                 |   6 +-
 drivers/irqchip/irq-gic-its-msi-parent.c |   2 +-
 drivers/of/base.c                        | 148 +++++++++++++++++------
 drivers/of/irq.c                         |   3 +-
 drivers/pci/controller/dwc/pci-imx6.c    |  12 +-
 drivers/pci/controller/pcie-apple.c      |   5 +-
 drivers/xen/grant-dma-ops.c              |   3 +-
 include/linux/of.h                       |  33 ++++-
 9 files changed, 152 insertions(+), 63 deletions(-)

-- 
2.34.1

You're missing a significant number of maintainers.

https://lore.kernel.org/all/20260226074245.3098486-1-vijayanand.jitta@oss.qualcomm.com/

From: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
To: robin.murphy@arm.com, will@kernel.org, joro@8bytes.org,
	robh@kernel.org, dmitry.baryshkov@oss.qualcomm.com,
	konrad.dybcio@oss.qualcomm.com, bjorn.andersson@oss.qualcomm.com,
	bod@kernel.org, conor+dt@kernel.org, krzk+dt@kernel.org,
	prakash.gupta@oss.qualcomm.com, vikash.garodia@oss.qualcomm.com
Cc: iommu@lists.linux.dev, linux-kernel@vger.kernel.org,
	devicetree@vger.kernel.org,
	Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
Subject: [RESEND,v8 0/3] of: parsing of multi #{iommu,msi}-cells in maps
Date: Thu, 26 Feb 2026 13:12:42 +0530	[thread overview]
Message-ID: <20260226074245.3098486-1-vijayanand.jitta@oss.qualcomm.com> 
(raw)

There's no point in resending since you aren't mailing the right list of 
people right now

deckard@sagittarius-a:~/Development/worktree/reviews/linux-next-reviews 
(linux-next-reviews) $ scripts/get_maintainer.pl 
0001-of-Add-convenience-wrappers-for-of_map_id.patch
Nipun Gupta <nipun.gupta@amd.com> (maintainer:AMD CDX BUS DRIVER)
Nikhil Agarwal <nikhil.agarwal@amd.com> (maintainer:AMD CDX BUS DRIVER)

<snip>

Please run scripts/get_maintainer.pl on each of your patches and include 
the right set.

---
bod

On 2/28/2026 3:59 AM, Bryan O'Donoghue wrote:
> 
> You're missing a significant number of maintainers.
> 
> https://lore.kernel.org/all/20260226074245.3098486-1-vijayanand.jitta@oss.qualcomm.com/
> 
> From: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
> To: robin.murphy@arm.com, will@kernel.org, joro@8bytes.org,
>     robh@kernel.org, dmitry.baryshkov@oss.qualcomm.com,
>     konrad.dybcio@oss.qualcomm.com, bjorn.andersson@oss.qualcomm.com,
>     bod@kernel.org, conor+dt@kernel.org, krzk+dt@kernel.org,
>     prakash.gupta@oss.qualcomm.com, vikash.garodia@oss.qualcomm.com
> Cc: iommu@lists.linux.dev, linux-kernel@vger.kernel.org,
>     devicetree@vger.kernel.org,
>     Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
> Subject: [RESEND,v8 0/3] of: parsing of multi #{iommu,msi}-cells in maps
> Date: Thu, 26 Feb 2026 13:12:42 +0530    [thread overview]
> Message-ID: <20260226074245.3098486-1-vijayanand.jitta@oss.qualcomm.com> (raw)
> 
> There's no point in resending since you aren't mailing the right list of people right now
> 
> deckard@sagittarius-a:~/Development/worktree/reviews/linux-next-reviews (linux-next-reviews) $ scripts/get_maintainer.pl 0001-of-Add-convenience-wrappers-for-of_map_id.patch
> Nipun Gupta <nipun.gupta@amd.com> (maintainer:AMD CDX BUS DRIVER)
> Nikhil Agarwal <nikhil.agarwal@amd.com> (maintainer:AMD CDX BUS DRIVER)
> 
> <snip>
> 
> Please run scripts/get_maintainer.pl on each of your patches and include the right set.
> 
> ---
> bod

Thanks for pointing this out.

I have sent v9 including all the relevant maintainers.

Thanks,
Vijay