On Wed, May 26, 2021 at 11:53 PM Will Deacon will@kernel.org wrote:
On Wed, May 26, 2021 at 01:13:22PM +0100, Will Deacon wrote:
On Tue, May 18, 2021 at 02:42:14PM +0800, Claire Chang wrote:
@@ -138,4 +160,9 @@ one for multimedia processing (named multimedia-memory@77000000, 64MiB). memory-region = <&multimedia_reserved>; /* ... */ };
- pcie_device: pcie_device@0,0 {
memory-region = <&restricted_dma_mem_reserved>;/* ... */- };
I still don't understand how this works for individual PCIe devices -- how is dev->of_node set to point at the node you have above?
I tried adding the memory-region to the host controller instead, and then I see it crop up in dmesg:
| pci-host-generic 40000000.pci: assigned reserved memory node restricted_dma_mem_reserved
but none of the actual PCI devices end up with 'dma_io_tlb_mem' set, and so the restricted DMA area is not used. In fact, swiotlb isn't used at all.
What am I missing to make this work with PCIe devices?
Aha, looks like we're just missing the logic to inherit the DMA configuration. The diff below gets things working for me.
I guess what was missing is the reg property in the pcie_device node. Will update the example dts.