Re: [PATCH] dma-iommu: Introduce API to reserve IOVA regions for dynamically created devices

[Jason Gunthorpe]

On Fri, Jul 17, 2026 at 12:44:54PM +0200, Konrad Dybcio wrote:

> I was kinda hoping there would be more buy-in to follow what PCIe
> does, but to my understanding you're opposed to it because "vpu_bus"
> is not dynamically discoverable.

PCIe allows describing devices in DT. What this weird vpu_bus thing
seems to be about is to actively avoid describing the devices in DT
while simultaenously treating them like devices. I think it makes no
sense..

IMHO the approach inverts the thing, you start the main driver then
use vpu_bus to dynamically create a bunch of struct device DMA handles
for the main driver to use.

I think it is much better if you start the main driver, use the new
component stuff:

https://docs.kernel.org/driver-api/component.html

To aggregate a driver from the struct device DMA handles that DT will
create automatically. ie the reversed flow, the struct devices
pre-exist created by DT instead of being created by code in your
driver.

Jason