Re: [PATCH v2 0/3] ACPI: arm64: FFH Operation Region support for FF-A (offset 2)

[Sudeep Holla]

On Wed, Sep 23, 2026 at 05:40:50AM -0700, Jamie Nguyen wrote:
> On Tue, Sep 22, 2026 at 07:06:02PM +0100, Sudeep Holla wrote:
> > Equally ugly. FF-A spec doesn't talk about ACPI FFH, so it doesn't
> > belong in FF-A driver.
> 
> Okay -- I'll move the ACPI-specific handling into ffh.c.
> 
> > So if on a platform, ASL has FFH with offset 2, we fail if FF-A driver
> > fails to initialise ? What if this FFH offset 2 is used in some other
> > device methods that need to be executed before FF-A module is inserted ?
> > We pull that device down as well ? Is that acceptable ?
> 
> You're right. With the current registration, offset 2 may be unavailable
> during initial enumeration or before module load. That's not suitable for
> AML.
> 
> > There is no state management with simple FFA_MSG_SEND_DIRECT_REQ2, it is
> > synchronous send request if you look at it along wih offset 0/1 and
> > without FF-A driver knowledge.
> 
> The request itself is synchronous and register-only. But the whole operation
> still shares FF-A state: version negotiation must be coordinated with other
> FF-A use, and X1 == 0 needs UUID lookup. It looks like
> FFA_PARTITION_INFO_GET_REGS is optional at the Non-secure physical instance
> according to DEN0077A Table 13.1. As such, I believe a portable
> implementation would need the shared RX/TX buffers. For example, if X1 is
> zero and that ABI is unavailable, UUID lookup would need to fall back to
> FFA_PARTITION_INFO_GET, whose results are returned through the caller's RX
> buffer.

I did try to come up something simpler and independent last evening and
this morning, far from completion and I am also thinking of 2 main changes
to it yet:
1. Maintain hash for receiver ID list
2. Drop the whole FFA_VERSION fuss as it must be dealt with in UEFI and
   that should be sufficient.

Of course not tested yet and even not sure this version is compile tested.
Also more checks needs to added like INFO_GET_REGS is used without check.

Regards,
Sudeep

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