kernel/include/linux/dma-direct.h, branch linux-5.2.y

dma-mapping: bypass indirect calls for dma-direct

2018-12-13T20:06:18Z

Avoid expensive indirect calls in the fast path DMA mapping operations by directly calling the dma_direct_* ops if we are using the directly mapped DMA operations. Signed-off-by: Christoph Hellwig Acked-by: Jesper Dangaard Brouer Tested-by: Jesper Dangaard Brouer Tested-by: Tony Luck

dma-direct: merge swiotlb_dma_ops into the dma_direct code

2018-12-13T20:06:17Z

While the dma-direct code is (relatively) clean and simple we actually have to use the swiotlb ops for the mapping on many architectures due to devices with addressing limits. Instead of keeping two implementations around this commit allows the dma-direct implementation to call the swiotlb bounce buffering functions and thus share the guts of the mapping implementation. This also simplified the dma-mapping setup on a few architectures where we don't have to differenciate which implementation to use. Signed-off-by: Christoph Hellwig Acked-by: Jesper Dangaard Brouer Tested-by: Jesper Dangaard Brouer Tested-by: Tony Luck

swiotlb: remove dma_mark_clean

2018-12-13T20:06:14Z

Instead of providing a special dma_mark_clean hook just for ia64, switch ia64 to use the normal arch_sync_dma_for_cpu hooks instead. This means that we now also set the PG_arch_1 bit for pages in the swiotlb buffer, which isn't stricly needed as we will never execute code out of the swiotlb buffer, but otherwise harmless. Signed-off-by: Christoph Hellwig Acked-by: Jesper Dangaard Brouer Tested-by: Jesper Dangaard Brouer Tested-by: Tony Luck

dma-direct: remove the mapping_error dma_map_ops method

2018-12-06T14:56:36Z

The dma-direct code already returns (~(dma_addr_t)0x0) on mapping failures, so we can switch over to returning DMA_MAPPING_ERROR and let the core dma-mapping code handle the rest. Signed-off-by: Christoph Hellwig Acked-by: Linus Torvalds

dma-direct: provide page based alloc/free helpers

2018-12-01T16:55:02Z

Some architectures support remapping highmem into DMA coherent allocations. To use the common code for them we need variants of dma_direct_{alloc,free}_pages that do not use kernel virtual addresses. Signed-off-by: Christoph Hellwig Reviewed-by: Robin Murphy

dma-direct: Make DIRECT_MAPPING_ERROR viable for SWIOTLB

2018-11-21T17:47:52Z

With the overflow buffer removed, we no longer have a unique address which is guaranteed not to be a valid DMA target to use as an error token. The DIRECT_MAPPING_ERROR value of 0 tries to at least represent an unlikely DMA target, but unfortunately there are already SWIOTLB users with DMA-able memory at physical address 0 which now gets falsely treated as a mapping failure and leads to all manner of misbehaviour. The best we can do to mitigate that is flip DIRECT_MAPPING_ERROR to the other commonly-used error value of all-bits-set, since the last single byte of memory is by far the least-likely-valid DMA target. Fixes: dff8d6c1ed58 ("swiotlb: remove the overflow buffer") Reported-by: John Stultz Tested-by: John Stultz Acked-by: Konrad Rzeszutek Wilk Signed-off-by: Robin Murphy Signed-off-by: Christoph Hellwig

swiotlb: remove the overflow buffer

2018-10-19T06:43:46Z

Like all other dma mapping drivers just return an error code instead of an actual memory buffer. The reason for the overflow buffer was that at the time swiotlb was invented there was no way to check for dma mapping errors, but this has long been fixed. Signed-off-by: Christoph Hellwig Acked-by: Catalin Marinas Reviewed-by: Robin Murphy Reviewed-by: Konrad Rzeszutek Wilk

dma-direct: implement complete bus_dma_mask handling

2018-10-01T14:28:03Z

Instead of rejecting devices with a too small bus_dma_mask we can handle by taking the bus dma_mask into account for allocations and bounce buffering decisions. Signed-off-by: Christoph Hellwig

dma-direct: add an explicit dma_direct_get_required_mask

2018-10-01T14:27:15Z

This is somewhat modelled after the powerpc version, and differs from the legacy fallback in use fls64 instead of pointlessly splitting up the address into low and high dwords and in that it takes (__)phys_to_dma into account. Signed-off-by: Christoph Hellwig Acked-by: Benjamin Herrenschmidt Reviewed-by: Robin Murphy

dma-mapping: merge direct and noncoherent ops

2018-09-20T07:01:15Z

All the cache maintainance is already stubbed out when not enabled, but merging the two allows us to nicely handle the case where cache maintainance is required for some devices, but not others. Signed-off-by: Christoph Hellwig Acked-by: Paul Burton # MIPS parts