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-rw-r--r--Documentation/kernel-parameters.txt3
-rw-r--r--include/linux/swiotlb.h1
-rw-r--r--include/trace/events/swiotlb.h3
-rw-r--r--lib/swiotlb.c18
4 files changed, 21 insertions, 4 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 37babf91f2cb..922dec8fa07e 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -3998,10 +3998,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
it if 0 is given (See Documentation/cgroup-v1/memory.txt)
swiotlb= [ARM,IA-64,PPC,MIPS,X86]
- Format: { <int> | force }
+ Format: { <int> | force | noforce }
<int> -- Number of I/O TLB slabs
force -- force using of bounce buffers even if they
wouldn't be automatically used by the kernel
+ noforce -- Never use bounce buffers (for debugging)
switches= [HW,M68k]
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 746ecebbd4ca..d2613536fd03 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -12,6 +12,7 @@ struct scatterlist;
enum swiotlb_force {
SWIOTLB_NORMAL, /* Default - depending on HW DMA mask etc. */
SWIOTLB_FORCE, /* swiotlb=force */
+ SWIOTLB_NO_FORCE, /* swiotlb=noforce */
};
extern enum swiotlb_force swiotlb_force;
diff --git a/include/trace/events/swiotlb.h b/include/trace/events/swiotlb.h
index 5e2e30a7efce..288c0c54a2b4 100644
--- a/include/trace/events/swiotlb.h
+++ b/include/trace/events/swiotlb.h
@@ -39,7 +39,8 @@ TRACE_EVENT(swiotlb_bounced,
__entry->size,
__print_symbolic(__entry->swiotlb_force,
{ SWIOTLB_NORMAL, "NORMAL" },
- { SWIOTLB_FORCE, "FORCE" }))
+ { SWIOTLB_FORCE, "FORCE" },
+ { SWIOTLB_NO_FORCE, "NO_FORCE" }))
);
#endif /* _TRACE_SWIOTLB_H */
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 68e8f49c7e06..ad1d2962d129 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;
}
@@ -541,8 +545,15 @@ static phys_addr_t
map_single(struct device *hwdev, phys_addr_t phys, size_t size,
enum dma_data_direction dir)
{
- 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);
}
@@ -707,6 +718,9 @@ 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.