dma-direct: only limit the mapping size if swiotlb could be used

Don't just check for a swiotlb buffer, but also if buffering might
be required for this particular device.

Fixes: 133d624b1cee ("dma: Introduce dma_max_mapping_size()")
Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index d7cec86..e269b6f 100644 (file)
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -399,11 +399,9 @@ int dma_direct_supported(struct device *dev, u64 mask)
 
 size_t dma_direct_max_mapping_size(struct device *dev)
 {
-       size_t size = SIZE_MAX;
-
        /* If SWIOTLB is active, use its maximum mapping size */
-       if (is_swiotlb_active())
-               size = swiotlb_max_mapping_size(dev);
-
-       return size;
+       if (is_swiotlb_active() &&
+           (dma_addressing_limited(dev) || swiotlb_force == SWIOTLB_FORCE))
+               return swiotlb_max_mapping_size(dev);
+       return SIZE_MAX;
 }