Subject: Re: [PATCH v6 3/3] iommu/arm-smmu-v3: Allow ATS to be always on

From: Jason Gunthorpe <[email-masked]>
Date: Thu, 28 May 2026 12:29:30 -0300

On Thu, May 28, 2026 at 03:24:40PM +0000, Pranjal Shrivastava wrote:

> > +	master->ats_always_on = true;
> > +
> > +	return arm_smmu_alloc_cd_tables(master);
> 
> Nit: I'm not sure if I'm getting this right, are we saying we *need* to
> allocate CDs for CXL.cache cases in the probe itself because STE.EATS
> requires Config=Translate with S1DSS in bypass?

Yeah, basically.

Effectively the ARM rules for enabling ATS and Bypass together require
a valid CD table pointer.

Jason