[patch] doc: fix an incorrect suggestion to pass NULL for PCI like buses

From: Matti Linnanvuori
Date: Mon Apr 28 2008 - 12:33:45 EST


From: Matti Linnanvuori <mattilinnanvuori@xxxxxxxxx>

Fix an incorrect suggestion to pass NULL to pci_alloc_consistent
for PCI like buses where devices don't have struct pci_dev (like ISA, EISA).

Signed-off-by: Matti Linnanvuori <mattilinnanvuori@xxxxxxxxx>

---

This patch is to be applied on top of
[patch v3] doc: DMA-mapping.txt has undeclared variables [Bug 10397]

--- linux-2.6/Documentation/DMA-mapping.txt 2008-04-28 19:09:36.124693500 +0300
+++ linux/Documentation/DMA-mapping.txt 2008-04-28 19:17:07.711024500 +0300
@@ -317,9 +317,9 @@ you should do:

cpu_addr = pci_alloc_consistent(pdev, size, &dma_handle);

-where pdev is a struct pci_dev *. You should pass NULL for PCI like buses
-where devices don't have struct pci_dev (like ISA, EISA). This may be
-called in interrupt context.
+where pdev is a struct pci_dev *. This may be called in interrupt context.
+You should use dma_alloc_coherent (see DMA-API.txt) for buses
+where devices don't have struct pci_dev (like ISA, EISA).

This argument is needed because the DMA translations may be bus
specific (and often is private to the bus which the device is attached


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