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* [PATCH v5 0/3]  of: parsing of multi #{iommu,msi}-cells in maps
@ 2026-01-18 18:11 Vijayanand Jitta
  2026-01-18 18:11 ` [PATCH v5 1/3] of: Add convenience wrappers for of_map_id() Vijayanand Jitta
                   ` (2 more replies)
  0 siblings, 3 replies; 7+ messages in thread
From: Vijayanand Jitta @ 2026-01-18 18:11 UTC (permalink / raw)
  To: robin.murphy, will, joro, robh, dmitry.baryshkov, konrad.dybcio,
	bjorn.andersson, bod, conor+dt, krzk+dt, prakash.gupta,
	vikash.garodia
  Cc: iommu, linux-kernel, devicetree, vijayanand.jitta

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. 

The motivation for this patchset originates from the multi-map use case
described in V1, which will be addressed in a subsequent series once the
current fixes for iommu-cell handling are concluded.

These changes have been tested on QEMU for the arm64 architecture. We
plan to perform more extensive testing based on community feedback.

[1] https://lore.kernel.org/all/20250627-video_cb-v3-0-51e18c0ffbce@quicinc.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                    |   5 +-
 drivers/iommu/of_iommu.c                 |  12 +-
 drivers/irqchip/irq-gic-its-msi-parent.c |   2 +-
 drivers/of/base.c                        | 146 +++++++++++++++++------
 drivers/of/irq.c                         |   3 +-
 drivers/pci/controller/dwc/pci-imx6.c    |  14 ++-
 drivers/pci/controller/pcie-apple.c      |   5 +-
 drivers/xen/grant-dma-ops.c              |  21 ++--
 include/linux/of.h                       |  44 ++++++-
 9 files changed, 179 insertions(+), 73 deletions(-)

-- 
2.34.1


^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2026-01-20  5:09 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
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2026-01-18 18:11 [PATCH v5 0/3] of: parsing of multi #{iommu,msi}-cells in maps Vijayanand Jitta
2026-01-18 18:11 ` [PATCH v5 1/3] of: Add convenience wrappers for of_map_id() Vijayanand Jitta
2026-01-18 18:11 ` [PATCH v5 2/3] of: factor arguments passed to of_map_id() into a struct Vijayanand Jitta
2026-01-18 18:11 ` [PATCH v5 3/3] of: Respect #{iommu,msi}-cells in maps Vijayanand Jitta
2026-01-18 21:04   ` kernel test robot
2026-01-20  5:08     ` Vijayanand Jitta
2026-01-18 21:57   ` kernel test robot

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