Subject: [PATCH 09/11] of: Make of_dma_get_range() work on bus nodes

From: Rob Herring <[email-masked]>
Date: Thu, 26 Sep 2019 19:24:53 -0500

From: Robin Murphy <[email-masked]>

Since the "dma-ranges" property is only valid for a node representing a
bus, of_dma_get_range() currently assumes the node passed in is a leaf
representing a device, and starts the walk from its parent. In cases
like PCI host controllers on typical FDT systems, however, where the PCI
endpoints are probed dynamically the initial leaf node represents the
'bus' itself, and this logic means we fail to consider any "dma-ranges"
describing the host bridge itself. Rework the logic such that
of_dma_get_range() works correctly starting from a bus node containing
"dma-ranges".

Signed-off-by: Robin Murphy <[email-masked]>
[robh: Allow for the bus child node to still be passed in]
Signed-off-by: Rob Herring <[email-masked]>
---
 drivers/of/address.c | 24 +++++-------------------
 1 file changed, 5 insertions(+), 19 deletions(-)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 887c0413f648..e918001c7798 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -922,18 +922,9 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
 	if (!node)
 		return -EINVAL;
 
-	while (1) {
-		struct device_node *parent;
-
-		naddr = of_n_addr_cells(node);
-		nsize = of_n_size_cells(node);
-
-		parent = __of_get_dma_parent(node);
-		of_node_put(node);
-
-		node = parent;
-		if (!node)
-			break;
+	while (node) {
+		naddr = of_bus_n_addr_cells(node);
+		nsize = of_bus_n_size_cells(node);
 
 		ranges = of_get_property(node, "dma-ranges", &len);
 
@@ -941,12 +932,7 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
 		if (ranges && len > 0)
 			break;
 
-		/*
-		 * At least empty ranges has to be defined for parent node if
-		 * DMA is supported
-		 */
-		if (!ranges)
-			break;
+		node = of_get_next_dma_parent(node);
 	}
 
 	if (!ranges) {
@@ -965,7 +951,7 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
 	 * size		: nsize cells
 	 */
 	dmaaddr = of_read_number(ranges, naddr);
-	*paddr = of_translate_dma_address(np, ranges);
+	*paddr = of_translate_dma_address(node, ranges + naddr);
 	if (*paddr == OF_BAD_ADDR) {
 		pr_err("translation of DMA address(%llx) to CPU address failed node(%pOF)\n",
 		       dmaaddr, np);
-- 
2.20.1

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