Re: [PATCH v2 0/3] arm-smmu: select suitable IOVA

[Jason Gunthorpe <jgg@ziepe.ca>]

On Thu, Apr 10, 2025 at 03:50:27PM -0700, Shyam Saini wrote:
> 
> Hi,
> 
> Currently, the MSI_IOVA_BASE address is hard-coded to 0x80000000,
> assuming that all platforms have this address available for MSI IOVA
> reservation. However, this is not always the case, as some platforms
> reserve this address for other purposes. Consequently, these platforms
> cannot reserve the MSI_IOVA_BASE address for MSI.
> 
> There was an [1] attempt to fix this problem by passing the MSI IOVA
> base as a kernel command line parameter.
> 
> This patch series aims to address the issue by introducing a new DTS
> property, "arm,smmu-faulty-msi-iova" which can be used to hold faulty
> MSI IOVA address. This property can be passed to ARM SMMU drivers
> via device tree so that the drivers can select appropriate MSI IOVA base
> address which doesn't intersect with the faulty MSI IOVA address.

I thought we already talked about this and you were not going to be
doing a DT proposal for a software knob?

And then you didn't even link to the recent discussion :(

https://lore.kernel.org/linux-iommu/20250403232619.GA681099@ziepe.ca/

It is easily solved in the smmuv3 driver without out any DT. Please
do that.

Jason