On Wed, Aug 26, 2015 at 02:52:02PM -0400, jglisse@xxxxxxxxxx wrote:
> From: Jérôme Glisse <jglisse@xxxxxxxxxx>
>
> Some device like GPU do things differently if swiotlb is in use. We
> use to rely on swiotlb_nr_tbl() to know if swiotlb was enabled or not
> but this is unreliable. Patch add a simple helpers to check if any of
Why is it unreliable?
> the dma_ops associated with a device points to the swiotlb functions,
> making swiotlb check reliable for a device.
>
> Signed-off-by: Jérôme Glisse <jglisse@xxxxxxxxxx>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Cc: Alex Deucher <alexander.deucher@xxxxxxx>
> Cc: Ben Skeggs <bskeggs@xxxxxxxxxx>
> Cc: Dave Airlie <airlied@xxxxxxxxxx>
> Cc: lkml@xxxxxxxxxxxxxxx
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> ---
> include/linux/dma-mapping.h | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index ac07ff0..eac911e 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -314,4 +314,22 @@ static inline int dma_mmap_writecombine(struct device *dev,
> #define dma_unmap_len_set(PTR, LEN_NAME, VAL) do { } while (0)
> #endif
>
> +
> +#ifdef CONFIG_SWIOTLB
> +static inline bool swiotlb_in_use(struct device *dev)
> +{
> + struct dma_map_ops *ops = get_dma_ops(dev);
> +
> + return (ops->map_sg == swiotlb_map_sg_attrs ||
> + ops->unmap_sg == swiotlb_unmap_sg_attrs ||
> + ops->map_page == swiotlb_map_page);
That won't work. What if we use xen-swiotlb which has different function
names?
> +}
> +#else
> +static inline bool swiotlb_in_use(struct device *dev)
> +{
> + return false;
> +}
> +#endif
> +
> +
> #endif
> --
> 2.1.0
>
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