Re: [PATCH 0/2] Add arm-smmu-v3 support for instcfg data override feature

[Rob Herring <robh@kernel.org>]

On Fri, Aug 07, 2026 at 04:25:11PM +0100, Peter Griffin wrote:
> Hi Will & Robin,
> 
> Thank you both for your review feedback.
> 
> On Mon, 27 Jul 2026 at 11:53, Robin Murphy <robin.murphy@arm.com> wrote:
> >
> > On 26/07/2026 2:16 pm, Will Deacon wrote:
> > > On Fri, Jul 24, 2026 at 01:39:41PM +0100, Peter Griffin wrote:
> > >> These two patches add support for a new "arm,instdata-override" DT property
> > >> that enables the override of the instruction/data attribute of incoming
> > >> traffic to Data by setting the INSTCFG override bits.
> > >>
> > >> It is intended to be specified when the smmu can't guarantee that these
> > >> attributes are provided correctly from the client device.
> > >
> > > This is going to need an in-tree user and a much more detailed
> > > description of what is being worked around before we consider this for
> > > inclusion.
> 
> Regarding an in-tree user, I haven't sent the Device Tree (DT) patch
> yet for Laguna SoC which adds the smmu nodes and this property because
> 1) I want to land the initial SoC/board DT first
> 2) I want agreement on the DT property name. Currently I used
> "arm,instdata-override" which is what downstream used. However, since
> this is intended to work around silicon errata something like
> "google,lga-instcfg-data-override" might be more appropriate?

Shrug.

Really, this is why we want SoC specific compatibles so work-arounds can 
be added without DT updates. But we've generally avoided doing that for 
SMMU for whatever reasons. Just make the property clearly sound like a 
mistake, not a feature you might want to use. I'd keep the arm prefix 
just so the next vendor thinks they can't use 'google' and creates the 
same property with their vendor prefix.

Rob