On Tue, Feb 9, 2021 at 1:33 PM Rob Herring <robh@xxxxxxxxxx> wrote: > > On Fri, Feb 05, 2021 at 02:26:40PM -0800, Saravana Kannan wrote: > > Not all DT bindings are mandatory bindings. Add support for optional DT > > bindings and mark iommus, iommu-map, dmas as optional DT bindings. > > I don't think we can say these are optional or not. It's got to be a > driver decision somehow. Right, so maybe the word "optional" isn't a good name for it. I can change that if you want. The point being, fw_devlink can't block the probe of this driver based on iommu property. We let the driver decide if it wants to -EPROBE_DEFER or not or however it wants to handle this. > For example, if IOMMU is optional, what happens with this sequence: > > driver probes without IOMMU > driver calls dma_map_?() > IOMMU driver probes > h/w accesses DMA buffer --> BOOM! Right. But how is this really related to fw_devlink? AFAICT, this is an issue even today. If the driver needs the IOMMU, then it needs to make sure the IOMMU has probed? What am I missing? -Saravana
