Re: [patch] [Bug 10397] DMA-mapping.txt code examples haveundeclared variables

From: Grant Grundler
Date: Sun Apr 06 2008 - 02:52:06 EST


On Sat, Apr 05, 2008 at 09:34:42PM -0700, Matti Linnanvuori wrote:
> From: Matti Linnanvuori <mattilinnanvuori@xxxxxxxxx>
>
> Fix undeclared variables.

Sorry? This changelog entry doesn't make sense to me since this patch
is for documentation and not a compiler error.

If you prefer them declared as C code, please try it this way:

+ struct pci_dev dev*;
+ size_t size;
dma_addr_t dma_handle;

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

and delete the verbage (plain text) that defines the parameters.

If you are confusing "dev" with "struct device *" and want to change
all the references to "pdev", please do the above *and* write something
like the following in the changelog:
To avoid confusion with struct device, rename ...

thanks!
grant

>
> Signed-off-by: Matti Linnanvuori <mattilinnanvuori@xxxxxxxxx>
>
> ---
>
> --- linux-2.6/Documentation/DMA-mapping.txt 2008-03-23 09:01:06.304511500 +0200
> +++ linux/Documentation/DMA-mapping.txt 2008-04-06 06:56:11.821314500 +0300
> @@ -315,9 +315,9 @@
>

> dma_addr_t dma_handle;
>
> - cpu_addr = pci_alloc_consistent(dev, size, &dma_handle);
> + cpu_addr = pci_alloc_consistent(pdev, size, &dma_handle);
>
> -where dev is a struct pci_dev *. You should pass NULL for PCI like buses
> +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.
>
> @@ -354,9 +354,9 @@
>
> To unmap and free such a DMA region, you call:
>
> - pci_free_consistent(dev, size, cpu_addr, dma_handle);
> + pci_free_consistent(pdev, size, cpu_addr, dma_handle);
>
> -where dev, size are the same as in the above call and cpu_addr and
> +where pdev, size are the same as in the above call and cpu_addr and
> dma_handle are the values pci_alloc_consistent returned to you.
> This function may not be called in interrupt context.
>
> @@ -371,9 +371,9 @@
>
> struct pci_pool *pool;
>
> - pool = pci_pool_create(name, dev, size, align, alloc);
> + pool = pci_pool_create(name, pdev, size, align, alloc);
>
> -The "name" is for diagnostics (like a kmem_cache name); dev and size
> +The "name" is for diagnostics (like a kmem_cache name); pdev and size
> are as above. The device's hardware alignment requirement for this
> type of data is "align" (which is expressed in bytes, and must be a
> power of two). If your device has no boundary crossing restrictions,
> @@ -472,11 +472,11 @@
> void *addr = buffer->ptr;
> size_t size = buffer->len;
>
> - dma_handle = pci_map_single(dev, addr, size, direction);
> + dma_handle = pci_map_single(pdev, addr, size, direction);
>
> and to unmap it:
>
> - pci_unmap_single(dev, dma_handle, size, direction);
> + pci_unmap_single(pdev, dma_handle, size, direction);
>
> You should call pci_unmap_single when the DMA activity is finished, e.g.
> from the interrupt which told you that the DMA transfer is done.
> @@ -493,17 +493,17 @@
> unsigned long offset = buffer->offset;
> size_t size = buffer->len;
>
> - dma_handle = pci_map_page(dev, page, offset, size, direction);
> + dma_handle = pci_map_page(pdev, page, offset, size, direction);
>
> ...
>
> - pci_unmap_page(dev, dma_handle, size, direction);
> + pci_unmap_page(pdev, dma_handle, size, direction);
>
> Here, "offset" means byte offset within the given page.
>
> With scatterlists, you map a region gathered from several regions by:
>
> - int i, count = pci_map_sg(dev, sglist, nents, direction);
> + int i, count = pci_map_sg(pdev, sglist, nents, direction);
> struct scatterlist *sg;
>
> for_each_sg(sglist, sg, count, i) {
> @@ -527,7 +527,7 @@
>
> To unmap a scatterlist, just call:
>
> - pci_unmap_sg(dev, sglist, nents, direction);
> + pci_unmap_sg(pdev, sglist, nents, direction);
>
> Again, make sure DMA activity has already finished.
>
> @@ -550,11 +550,11 @@
> So, firstly, just map it with pci_map_{single,sg}, and after each DMA
> transfer call either:
>
> - pci_dma_sync_single_for_cpu(dev, dma_handle, size, direction);
> + pci_dma_sync_single_for_cpu(pdev, dma_handle, size, direction);
>
> or:
>
> - pci_dma_sync_sg_for_cpu(dev, sglist, nents, direction);
> + pci_dma_sync_sg_for_cpu(pdev, sglist, nents, direction);
>
> as appropriate.
>
> @@ -562,7 +562,7 @@
> finish accessing the data with the cpu, and then before actually
> giving the buffer to the hardware call either:
>
> - pci_dma_sync_single_for_device(dev, dma_handle, size, direction);
> + pci_dma_sync_single_for_device(pdev, dma_handle, size, direction);
>
> or:
>
> @@ -739,7 +739,7 @@
>
> dma_addr_t dma_handle;
>
> - dma_handle = pci_map_single(dev, addr, size, direction);
> + dma_handle = pci_map_single(pdev, addr, size, direction);
> if (pci_dma_mapping_error(dma_handle)) {
> /*
> * reduce current DMA mapping usage,
>
>
>
>
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