Re: [PATCH v5 08/12] PCI: imx6: Config look up table(LUT) to support MSI ITS and IOMMU for i.MX95

Frank Li
2024-06-04T15:48:14Z

On Tue, Jun 04, 2024 at 04:25:51PM +0100, Marc Zyngier wrote:
> On Mon, 03 Jun 2024 22:04:23 +0100,
> Frank Li <Frank.li@nxp.com> wrote:
> >
> > iommu may share one stream id for multi-devices. but ITS MSI can't. each
> > device's MSI index start from 0. It needs difference stream id for each
> > device.
>
> That's not quite true. We go through all sort of hoops to find about
> device aliasing on PCI and allow devices that translate into the same
> DID to get MSIs.

Could you please point me the code location? I remember I met error when I
try to enable MSI for EP support one year ago.

https://lore.kernel.org/imx/20221124055036.1630573-1-Frank.Li@nxp.com/

I remember that it is failure try to allocate more irqs with the same DID.

Frank

>
> Of course, just like the IOMMU, you lose any form of isolation, but
> you get what you pay for.

Anyways, if there are one quirk in PCI system, bridge driver can detect
PCI devices add/remove. it will be better if assign stream ID as need,
compared with static allocate.

>
> M.
>
> --
> Without deviation from the norm, progress is not possible.