On Tuesday, October 27, 2026 9:33 PM Jason Gunthorpe wrote: > On Tue, Oct 27, 2026 at 12:42:32PM +0900, Mikko Perttunen wrote: > > > > This page-side use predates the series, so the fault is not itself a v2 > > > regression. Is dma_buf_sgt_attach() valid for this call site, or does > > > Tegra > > > need a page/physical mapping type first? > > > > Sounds like a bug in TegraDRM; we should be using the DMA addr/length > > for the explicit IOMMU mapping as the sgt attachment is for the dummy > > DRM device explicitly intended to give us physical addresses. > > No, you cannot connect dmabuf to an iommu_domain. It is 100% always > illegal. DMABUF does not support this. Do not pass sg_dma to iommu > functions either.
Sure, I agree -- so let's say it's a bug on top of the baseline crimes TegraDRM commits :) > > > I'm currently in the process of removing the whole explicit IOMMU path > > so if this only occurs with CONFIG_DMABUF_DEBUG enabled, I don't think > > there's a pressing need to fix this before then. > > Yes I think this is probably the only way to fix it :| You have to > always use the DMA API > > Jason >
