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| author | Geert Uytterhoeven <geert+renesas@glider.be> | 2016-12-16 14:28:42 +0100 |
|---|---|---|
| committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2016-12-19 09:05:20 -0500 |
| commit | fff5d99225107f5f13fe4a9805adc2a1c4b5fb00 (patch) | |
| tree | 0b9748236ea4580bc44f9a24ec27c215cb46ed9b /lib | |
| parent | ae7871be189cb41184f1e05742b4a99e2c59774d (diff) | |
| download | lwn-fff5d99225107f5f13fe4a9805adc2a1c4b5fb00.tar.gz lwn-fff5d99225107f5f13fe4a9805adc2a1c4b5fb00.zip | |
swiotlb: Add swiotlb=noforce debug option
On architectures like arm64, swiotlb is tied intimately to the core
architecture DMA support. In addition, ZONE_DMA cannot be disabled.
To aid debugging and catch devices not supporting DMA to memory outside
the 32-bit address space, add a kernel command line option
"swiotlb=noforce", which disables the use of bounce buffers.
If specified, trying to map memory that cannot be used with DMA will
fail, and a rate-limited warning will be printed.
Note that io_tlb_nslabs is set to 1, which is the minimal supported
value.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/swiotlb.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/lib/swiotlb.c b/lib/swiotlb.c index a32dce6d5101..9def738af4f4 100644 --- a/lib/swiotlb.c +++ b/lib/swiotlb.c @@ -106,8 +106,12 @@ setup_io_tlb_npages(char *str) } if (*str == ',') ++str; - if (!strcmp(str, "force")) + if (!strcmp(str, "force")) { swiotlb_force = SWIOTLB_FORCE; + } else if (!strcmp(str, "noforce")) { + swiotlb_force = SWIOTLB_NO_FORCE; + io_tlb_nslabs = 1; + } return 0; } @@ -543,8 +547,15 @@ static phys_addr_t map_single(struct device *hwdev, phys_addr_t phys, size_t size, enum dma_data_direction dir, unsigned long attrs) { - dma_addr_t start_dma_addr = phys_to_dma(hwdev, io_tlb_start); + dma_addr_t start_dma_addr; + + if (swiotlb_force == SWIOTLB_NO_FORCE) { + dev_warn_ratelimited(hwdev, "Cannot do DMA to address %pa\n", + &phys); + return SWIOTLB_MAP_ERROR; + } + start_dma_addr = phys_to_dma(hwdev, io_tlb_start); return swiotlb_tbl_map_single(hwdev, start_dma_addr, phys, size, dir, attrs); } @@ -721,6 +732,9 @@ static void swiotlb_full(struct device *dev, size_t size, enum dma_data_direction dir, int do_panic) { + if (swiotlb_force == SWIOTLB_NO_FORCE) + return; + /* * Ran out of IOMMU space for this operation. This is very bad. * Unfortunately the drivers cannot handle this operation properly. |