Re: [PATCH 1/2] iommu: Add device ATS not supported capability

[Jason Gunthorpe]

On Tue, Mar 03, 2026 at 03:03:47PM +0000, Shameer Kolothum wrote:
> @@ -271,6 +271,8 @@ enum iommu_cap {
>  	 */
>  	IOMMU_CAP_DEFERRED_FLUSH,
>  	IOMMU_CAP_DIRTY_TRACKING,	/* IOMMU supports dirty tracking */
> +	/* ATS is not supported and not used on this device */
> +	IOMMU_CAP_PCI_ATS_NOT_SUPPORTED,

Actually, on second thought, the kdoc should have more details about
what supported means.

Does this mean ATS is available and could be turned on ?

Or does it mean ATS is on *right now* ?

The drivers should be changing ATS dynamically depending on what
domain is attached.

I think the implementation follows the first option?

Jason