On 2022-09-08 17:32:47 -0500, Rob Herring wrote: > On Mon, Sep 05, 2022 at 07:08:29PM +0200, Thierry Reding wrote: > > From: Thierry Reding <treding@xxxxxxxxxx> > > > > This adds the "iommu-addresses" property to reserved-memory nodes, which > > allow describing the interaction of memory regions with IOMMUs. Two use- > > cases are supported: > > > > 1. Static mappings can be described by pairing the "iommu-addresses" > > property with a "reg" property. This is mostly useful for adopting > > firmware-allocated buffers via identity mappings. One common use- > > case where this is required is if early firmware or bootloaders > > have set up a bootsplash framebuffer that a display controller is > > actively scanning out from during the operating system boot > > process. > > > > 2. If an "iommu-addresses" property exists without a "reg" property, > > the reserved-memory node describes an IOVA reservation. Such memory > > regions are excluded from the IOVA space available to operating > > system drivers and can be used for regions that must not be used to > > map arbitrary buffers. > > > > Each mapping or reservation is tied to a specific device via a phandle > > to the device's device tree node. This allows a reserved-memory region > > to be reused across multiple devices. > > > > Signed-off-by: Thierry Reding <treding@xxxxxxxxxx> > > --- > > Changes in v8: > > - include validation warning fixes that had crept into an unrelated patch > > > > Changes in v7: > > - keep reserved-memory.txt to avoid broken references > > > > Changes in v6: > > - add device phandle to iommu-addresses property in examples > > - remove now unused dt-bindings/reserved-memory.h header > > > > .../reserved-memory/reserved-memory.yaml | 70 +++++++++++++++++++ > > 1 file changed, 70 insertions(+) > > Thanks for being persistent with this. It looks good to me. > > Reviewed-by: Rob Herring <robh@xxxxxxxxxx> > > I really don't like new common bindings with only 1 user, so I hope the > Asahi folks chime in here. Or really anyone else look at it. The Asahi WIP display controller/processor driver uses this binding with static non 1:1 mappings. The binding is sufficient for our needs our needs. Janne
