diff mbox

[04/15] swiotlb: remove unnecessary swiotlb_bus_to_virt

Message ID 1247187904-31999-5-git-send-email-fujita.tomonori@lab.ntt.co.jp
State Not Applicable
Headers show

Commit Message

FUJITA Tomonori July 10, 2009, 1:04 a.m. UTC
swiotlb_bus_to_virt is unncessary; we can use swiotlb_bus_to_phys and
phys_to_virt instead.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
---
 arch/powerpc/kernel/dma-swiotlb.c |   10 ----------
 lib/swiotlb.c                     |   34 ++++++++++++++++------------------
 2 files changed, 16 insertions(+), 28 deletions(-)

Comments

Becky Bruce July 14, 2009, 2:17 a.m. UTC | #1
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@lab.ntt.co.jp>
> ---
> 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
>
> --
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FUJITA Tomonori July 14, 2009, 5:08 a.m. UTC | #2
On Mon, 13 Jul 2009 21:17:21 -0500
Becky Bruce <beckyb@kernel.crashing.org> wrote:

> 
> 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,

Right,

> 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.

Oops, I overlooked this. However, as you said, this is not a problem
with the current code.


>  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 think that it's IA64's optimization (it's a NULL function on X86
like POWERPC). It's defined in arch/ia64/mm/init.c. Looks like POWERPC
could use this optimization, I guess.

dma_mark_clean() just modifies the page flag (what it needs is struct
page) so I think that we can make it take a paddr.


> 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.

Ok, I'll do.


Thanks,
Benjamin Herrenschmidt July 16, 2009, 3:40 a.m. UTC | #3
On Mon, 2009-07-13 at 21:17 -0500, Becky Bruce wrote:
> 
> phys_to_virt (also, virt_to_phys) is invalid for highmem addresses on  
> ppc. 

I would be surprised if x86 was any different here. Most of our highmem
implementation comes straight from x86 :-)

Cheers,
Ben.
diff mbox

Patch

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