Re: [PATCH 2/2] firmware: arm_ffa: Fall back to minimum buffer size if RXTX_MAP fails

[Seth Forshee]

On Tue, Jun 02, 2026 at 04:48:11PM +0100, Sudeep Holla wrote:
> On Mon, Jun 01, 2026 at 03:45:12PM -0500, Seth Forshee wrote:
> > FFA_FEATURES only supports a maximum size value for RXTX_MAP in v1.2+.
> > Older implementations may still reject larger sizes, which can happen
> > when the minimum size is rounded up to the page size when PAGE_SIZE >
> > 4K.
> > 
> > Fall back to the minimum size when RXTX_MAP fails with
> > INVALID_PARAMETERS to fix the regression on these platforms. This also
> > has the side effect of falling back for v1.2+ with a maximum of 0 (i.e.
> > no maximum), where the rounded-up value isn't expected to be rejected,
> > but there's no harm in retrying with a smaller size and it might even be
> > of benefit for a non-compliant SPMC.
> > 
> 
> Is this needed on any of your platforms ? I don't want to push a solution
> or fallback/workaround if there are no users for it.

Yes, we have platforms for which commit 83210251fd70 causes RXTX_MAP
failures with page sizes larger than 4K.

Thanks,
Seth