Re: [PATCH v4 0/5] Add support for Broadcom BCM2712 IOMMU driver (Raspberry Pi 5)

[Daniel Drake]

On 03/09/2026 19:14, Jim Quinlan wrote:
> I wish you had kept the dma-iova offset hack but I understand why you
> did not.


Well, having an initial iommu driver upstream will provide a good base 
on top of which we can work on that specific problem. It'll need some 
consideration/discussion to be done in a way that is not regarded as a 
hack. I might come back to this later, time permitting.

> I've built and successfully tested your driver on the> Broadcom 
sister chip of the RpI 5.  I am mostly interested in the
> iommu attached to the PCIe controller.  I tested this by running
> multiple tests where 10MiB is sent by a Wifi chip.  Data integrity was
> validated of course.
>
> I did not use the driver code as is.  I tried merely decrementing the
> MMMU_PT_PA_BASE value for the 4GB iova-offset required for our
> configuration, but that did not work for some reason.  So I just
> hacked in some iova conversions and got it working.

Thanks for the review and testing! I'll send an updated version that 
removes the blocking domain, hopefully that will be ready for inclusion.

Daniel