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Date: Tue, 4 Jun 2024 11:47:58 -0400
From: Frank Li <Frank.li@nxp.com>
To: Marc Zyngier <maz@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>, Bjorn Helgaas <helgaas@kernel.org>,
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Subject: Re: [PATCH v5 08/12] PCI: imx6: Config look up table(LUT) to support
 MSI ITS and IOMMU for i.MX95
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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.