of_get_dma_range uses (of_bus *)->count_cells to look up the #cells for addresses and sizes. It tries to do so for the current device node and for the parent tree. count_cells defaults to of_bus_default_count_cells, which _starts_ looking at the parent node already, and then upwards. The correct way is to use of_simple_*_cells for the current node, and count_cells(dev) for the parent tree.
Signed-off-by: Oleksii Moisieiev <[email protected]> Reviewed-by: Volodymyr Babchuk <[email protected]> Signed-off-by: Torsten Duwe <[email protected]> Reviewed-by: Oleksii Moisieiev <[email protected]> --- Here is the original, very detailed analysis and explanation [edited] : According to the Section 2.3.9 of the Device Tree specification[0] the format of the value of the dma-ranges property is an arbitrary number of triplets of (child-bus-address, parent-bus-address, length). Where: * The child-bus-address is a physical address within the child busâ address space. The number of cells to represent the address depends on the bus and can be determined from the #address-cells of this node (the node in which the dma-ranges property appears). * The parent-bus-address is a physical address within the parent busâ address space. The number of cells to represent the parent address is bus dependent and can be determined from the #address-cells property of the node that defines the parentâs address space. * The length specifies the size of the range in the childâs address space. The number of cells to represent the size can be determined from the #size-cells of this node (the node in which the dma-ranges property appears) This description matches comments in the of_addr source code. But the actual implementation does not match the specification. 'of_match_bus' returns address-cells and size-cells of the parent device. That's why the following calls were used to receive addr_cells and size_cells of the current device: - of_simple_addr_cells - of_simple_size_cells This fix was tested on RPI5 board with both device types: directly connected (e.g Serial) and connected over PCIe (e.g ethernet). For example when dma_ranges are parsing the following device tree structure: / { pcie2: { #address-cells = <3>; #size-cells = <2>; // 64GB system RAM space at PCIe 10_00000000 dma-ranges = <0x02000000 0x00 0x00000000 0x1f 0x00000000 0x00 0x00400000>, <0x43000000 0x10 0x00000000 0x00 0x00000000 0x10 0x00000000>; rp1: { #address-cells = <2>; #size-cells = <2>; dma-ranges = // inbound RP1 1x_xxxxxxxx -> PCIe 1x_xxxxxxxx <0x10 0x00000000 0x43000000 0x10 0x00000000 0x10 0x00000000>, // inbound RP1 c0_40xxxxxx -> PCIe 00_00xxxxxx <0xc0 0x40000000 0x02000000 0x0 0x00000000 0x0 0x00400000>, // inbound RP1 0x_xxxxxxxx -> PCIe 1x_xxxxxxxx <0x00 0x00000000 0x02000000 0x10 0x00000000 0x10 0x00000000>; }; }; }; So when we parse ranges on rp1, #address-cells of the rp1 node should be taken into account. In the provided example we have the following format: pcie2: #addres-cells = <0x3>; #size-cells = <0x2>; dma-ranges = < addr_hi addr_mid addr_lo trans_addr_hi trans_addr_lo size_hi size_lo>; rp1: #addres-cells = <0x2>; #size-cells = <0x2>; dma-ranges = < addr_hi addr_lo trans_addr_hi trans_addr_mid trans_addr_lo size_hi size_lo>; of_get_dma_range searches for the first dev with dma_ranges and then executes of_match_bus which follows by count_cells call for both device and parent. count_cells returns #address-cells for the parent device to the caller. So in the provided example address cells should be 2 for rp1, but we get 3 when using count_cells. This breaks address translation and is fixed in the provided patch by using the of_simple_addr_cells call, which will return correct address-cells for the node. This matches the requirements of the device-tree specification. [0] https://readthedocs.org/projects/devicetree-specification/downloads/pdf/latest/ Signed-off-by: Oleksii Moisieiev <[email protected]> Reviewed-by: Volodymyr Babchuk <[email protected]> --- drivers/core/of_addr.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/core/of_addr.c b/drivers/core/of_addr.c index 250dd175b55..823a4d70a6b 100644 --- a/drivers/core/of_addr.c +++ b/drivers/core/of_addr.c @@ -374,16 +374,16 @@ int of_get_dma_range(const struct device_node *dev, phys_addr_t *cpu, } /* Get the address sizes both for the bus and its parent */ - bus_node = of_match_bus((struct device_node*)dev); - bus_node->count_cells(dev, &na, &ns); + na = of_simple_addr_cells(dev); + ns = of_simple_size_cells(dev); if (!OF_CHECK_COUNTS(na, ns)) { printf("Bad cell count for %s\n", of_node_full_name(dev)); ret = -EINVAL; goto out_parent; } - bus_node = of_match_bus(parent); - bus_node->count_cells(parent, &pna, &pns); + bus_node = of_match_bus((struct device_node *)dev); + bus_node->count_cells(dev, &pna, &pns); if (!OF_CHECK_COUNTS(pna, pns)) { printf("Bad cell count for %s\n", of_node_full_name(parent)); ret = -EINVAL; -- 2.51.0
