> This is not a new dt property, the "iommus" property is an existing property
> that is parsed by the Nvidia implementation of the arm-smmu driver.
>
> Here is a snippet from the device tree:
>
> smmu_niso0: iommu@12000000 {
> compatible = "nvidia,tegra234-smmu", "nvidia,smmu-500";
> ...
> }
>
> /* MGBE0 */
> ethernet@6800000 {
> compatible = "nvidia,tegra234-mgbe";
> ...
> iommus = <&smmu_niso0 TEGRA234_SID_MGBE>;
> ...
> }
>
> /* MGBE1 */
> ethernet@6900000 {
> compatible = "nvidia,tegra234-mgbe";
> ...
> iommus = <&smmu_niso0 TEGRA234_SID_MGBE_VF1>;
> ...
> }
What i was meaning does the nvidia,tegra234-mgbe binding allow iommus?
I just checked, yes it does.
> If the iommus property is missing completely from the MGBE's device tree node it
> causes secure read/write errors which spam the kernel log and can cause crashes.
>
> I can add the fallback in V2 with a warning if that is preferred.
The fact it crashed makes me think it is optional. Any existing users
must work, otherwise it would crash, and then be debugged. I guess you
are pushing the usage further, and so have come across this condition.
Is the iommus a SoC property, or a board property? If it is a SoC
property, could you review all the SoC .dtsi files and fix up any
which are missing the property?
Adding a warning is O.K, but ideally the missing property should be
added first.
The merge window is open now, so patches will need to wait two weeks.
Andrew
