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authorGeert Uytterhoeven <geert+renesas@glider.be>2016-12-16 16:28:42 +0300
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2016-12-19 17:05:20 +0300
commitfff5d99225107f5f13fe4a9805adc2a1c4b5fb00 (patch)
tree0b9748236ea4580bc44f9a24ec27c215cb46ed9b /lib
parentae7871be189cb41184f1e05742b4a99e2c59774d (diff)
downloadlinux-fff5d99225107f5f13fe4a9805adc2a1c4b5fb00.tar.xz
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.c18
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.