On Fri, 2017-06-16 at 20:10 +0200, Christoph Hellwig wrote:
> Besides removing the last instance of the set_dma_mask method this also
> reduced the code duplication.
What is your rationale here ? (I have missed patch 0 it seems).
dma_supported() was supposed to be pretty much a "const" function
simply informing whether a given setup is possible. Having it perform
an actual switch of ops seems to be pushing it...
What if a driver wants to test various dma masks and then pick one ?
Where does the API documents that if a driver calls dma_supported() it
then *must* set the corresponding mask and use that ?
I don't like a function that is a "boolean query" like this one to have
such a major side effect.
>From an API standpoint, dma_set_mask() is when the mask is established,
and thus when the ops switch should happen.
Ben.
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> arch/powerpc/platforms/cell/iommu.c | 25 +++++++++----------------
> 1 file changed, 9 insertions(+), 16 deletions(-)
>
> diff --git a/arch/powerpc/platforms/cell/iommu.c b/arch/powerpc/platforms/cell/iommu.c
> index 497bfbdbd967..29d4f96ed33e 100644
> --- a/arch/powerpc/platforms/cell/iommu.c
> +++ b/arch/powerpc/platforms/cell/iommu.c
> @@ -644,20 +644,14 @@ static void dma_fixed_unmap_sg(struct device *dev, struct scatterlist *sg,
> direction, attrs);
> }
>
> -static int dma_fixed_dma_supported(struct device *dev, u64 mask)
> -{
> - return mask == DMA_BIT_MASK(64);
> -}
> -
> -static int dma_set_mask_and_switch(struct device *dev, u64 dma_mask);
> +static int dma_suported_and_switch(struct device *dev, u64 dma_mask);
>
> static const struct dma_map_ops dma_iommu_fixed_ops = {
> .alloc = dma_fixed_alloc_coherent,
> .free = dma_fixed_free_coherent,
> .map_sg = dma_fixed_map_sg,
> .unmap_sg = dma_fixed_unmap_sg,
> - .dma_supported = dma_fixed_dma_supported,
> - .set_dma_mask = dma_set_mask_and_switch,
> + .dma_supported = dma_suported_and_switch,
> .map_page = dma_fixed_map_page,
> .unmap_page = dma_fixed_unmap_page,
> .mapping_error = dma_iommu_mapping_error,
> @@ -952,11 +946,8 @@ static u64 cell_iommu_get_fixed_address(struct device *dev)
> return dev_addr;
> }
>
> -static int dma_set_mask_and_switch(struct device *dev, u64 dma_mask)
> +static int dma_suported_and_switch(struct device *dev, u64 dma_mask)
> {
> - if (!dev->dma_mask || !dma_supported(dev, dma_mask))
> - return -EIO;
> -
> if (dma_mask == DMA_BIT_MASK(64) &&
> cell_iommu_get_fixed_address(dev) != OF_BAD_ADDR) {
> u64 addr = cell_iommu_get_fixed_address(dev) +
> @@ -965,14 +956,16 @@ static int dma_set_mask_and_switch(struct device *dev, u64 dma_mask)
> dev_dbg(dev, "iommu: fixed addr = %llx\n", addr);
> set_dma_ops(dev, &dma_iommu_fixed_ops);
> set_dma_offset(dev, addr);
> - } else {
> + return 1;
> + }
> +
> + if (dma_iommu_dma_supported(dev, dma_mask)) {
> dev_dbg(dev, "iommu: not 64-bit, using default ops\n");
> set_dma_ops(dev, get_pci_dma_ops());
> cell_dma_dev_setup(dev);
> + return 1;
> }
>
> - *dev->dma_mask = dma_mask;
> -
> return 0;
> }
>
> @@ -1127,7 +1120,7 @@ static int __init cell_iommu_fixed_mapping_init(void)
> cell_iommu_setup_window(iommu, np, dbase, dsize, 0);
> }
>
> - dma_iommu_ops.set_dma_mask = dma_set_mask_and_switch;
> + dma_iommu_ops.dma_supported = dma_suported_and_switch;
> set_pci_dma_ops(&dma_iommu_ops);
>
> return 0;
--
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