Re: [PATCH 04/15] swiotlb: remove unnecessary swiotlb_bus_to_virt
From: Becky Bruce
Date: Mon Jul 13 2009 - 22:24:07 EST
On Jul 9, 2009, at 8:04 PM, FUJITA Tomonori wrote:
swiotlb_bus_to_virt is unncessary; we can use swiotlb_bus_to_phys and
phys_to_virt instead.
phys_to_virt (also, virt_to_phys) is invalid for highmem addresses on
ppc. In most of the uses in this file, it doesn't matter, as the
iotlb buffers themselves are alloc'd out of lowmem, but the
dma_mark_clean() calls could happen on a highmem addr. Currently, on
powerpc, dma_mark_clean() doesn't do anything, so it isn't a
functional problem. I'm fine with the bulk of this patch, because in
reality, if I need to do something with a virtual address of a highmem
page, I have to get a kmap for the page. So the existing
swiotlb_bus_to_virt isn't really helping.
What is dma_mark_clean used for? Could it be made to take a paddr,
and let the implementation deal with making sure there's a valid vaddr
for the actual "clean" operation?
I'd also like to see a comment with swiotlb_virt_to_bus() that notes
that it should only be called on addresses in lowmem.
Cheers,
Becky
Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
---
arch/powerpc/kernel/dma-swiotlb.c | 10 ----------
lib/swiotlb.c | 34 +++++++++++++++
+------------------
2 files changed, 16 insertions(+), 28 deletions(-)
diff --git a/arch/powerpc/kernel/dma-swiotlb.c b/arch/powerpc/kernel/
dma-swiotlb.c
index 68ccf11..41534ae 100644
--- a/arch/powerpc/kernel/dma-swiotlb.c
+++ b/arch/powerpc/kernel/dma-swiotlb.c
@@ -24,16 +24,6 @@
int swiotlb __read_mostly;
unsigned int ppc_swiotlb_enable;
-void *swiotlb_bus_to_virt(struct device *hwdev, dma_addr_t addr)
-{
- unsigned long pfn = PFN_DOWN(swiotlb_bus_to_phys(hwdev, addr));
- void *pageaddr = page_address(pfn_to_page(pfn));
-
- if (pageaddr != NULL)
- return pageaddr + (addr % PAGE_SIZE);
- return NULL;
-}
-
dma_addr_t swiotlb_phys_to_bus(struct device *hwdev, phys_addr_t
paddr)
{
return paddr + get_dma_direct_offset(hwdev);
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index dc1cd1f..1a89c84 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -130,11 +130,6 @@ static dma_addr_t swiotlb_virt_to_bus(struct
device *hwdev,
return swiotlb_phys_to_bus(hwdev, virt_to_phys(address));
}
-void * __weak swiotlb_bus_to_virt(struct device *hwdev, dma_addr_t
address)
-{
- return phys_to_virt(swiotlb_bus_to_phys(hwdev, address));
-}
-
int __weak swiotlb_arch_address_needs_mapping(struct device *hwdev,
dma_addr_t addr, size_t size)
{
@@ -307,9 +302,10 @@ address_needs_mapping(struct device *hwdev,
dma_addr_t addr, size_t size)
return swiotlb_arch_address_needs_mapping(hwdev, addr, size);
}
-static int is_swiotlb_buffer(char *addr)
+static int is_swiotlb_buffer(phys_addr_t paddr)
{
- return addr >= io_tlb_start && addr < io_tlb_end;
+ return paddr >= virt_to_phys(io_tlb_start) &&
+ paddr < virt_to_phys(io_tlb_end);
}
/*
@@ -582,11 +578,13 @@ EXPORT_SYMBOL(swiotlb_alloc_coherent);
void
swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
- dma_addr_t dma_handle)
+ dma_addr_t dev_addr)
{
+ phys_addr_t paddr = swiotlb_bus_to_phys(hwdev, dev_addr);
+
WARN_ON(irqs_disabled());
- if (!is_swiotlb_buffer(vaddr))
- free_pages((unsigned long) vaddr, get_order(size));
+ if (!is_swiotlb_buffer(paddr))
+ free_pages((unsigned long)vaddr, get_order(size));
else
/* DMA_TO_DEVICE to avoid memcpy in unmap_single */
do_unmap_single(hwdev, vaddr, size, DMA_TO_DEVICE);
@@ -671,19 +669,19 @@ EXPORT_SYMBOL_GPL(swiotlb_map_page);
static void unmap_single(struct device *hwdev, dma_addr_t dev_addr,
size_t size, int dir)
{
- char *dma_addr = swiotlb_bus_to_virt(hwdev, dev_addr);
+ phys_addr_t paddr = swiotlb_bus_to_phys(hwdev, dev_addr);
BUG_ON(dir == DMA_NONE);
- if (is_swiotlb_buffer(dma_addr)) {
- do_unmap_single(hwdev, dma_addr, size, dir);
+ if (is_swiotlb_buffer(paddr)) {
+ do_unmap_single(hwdev, phys_to_virt(paddr), size, dir);
return;
}
if (dir != DMA_FROM_DEVICE)
return;
- dma_mark_clean(dma_addr, size);
+ dma_mark_clean(phys_to_virt(paddr), size);
}
void swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
@@ -708,19 +706,19 @@ static void
swiotlb_sync_single(struct device *hwdev, dma_addr_t dev_addr,
size_t size, int dir, int target)
{
- char *dma_addr = swiotlb_bus_to_virt(hwdev, dev_addr);
+ phys_addr_t paddr = swiotlb_bus_to_phys(hwdev, dev_addr);
BUG_ON(dir == DMA_NONE);
- if (is_swiotlb_buffer(dma_addr)) {
- sync_single(hwdev, dma_addr, size, dir, target);
+ if (is_swiotlb_buffer(paddr)) {
+ sync_single(hwdev, phys_to_virt(paddr), size, dir, target);
return;
}
if (dir != DMA_FROM_DEVICE)
return;
- dma_mark_clean(dma_addr, size);
+ dma_mark_clean(phys_to_virt(paddr), size);
}
void
--
1.6.0.6
--
To unsubscribe from this list: send the line "unsubscribe linux-
kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/