* [Query] doubt on parameters passed to dma_map_single_attrs() API
@ 2016-03-22 10:23 ` Sodagudi Prasad
0 siblings, 0 replies; 4+ messages in thread
From: Sodagudi Prasad @ 2016-03-22 10:23 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, linux; +Cc: shashim, sboyd, psodagud
Hi All,
Would like to check whether the dma_map_single_attrs() API, can accept
ptr variable from high memory or not?
If we pass the memory pointer, which is pointing high memory does not
work with virt_to_page API.
10 static inline dma_addr_t dma_map_single_attrs(struct device *dev,
void *ptr,
11 size_t size,
12 enum
dma_data_direction dir,
13 struct dma_attrs
*attrs)
14 {
15 const struct dma_map_ops *ops = get_dma_ops(dev);
16 dma_addr_t addr;
17
18 kmemcheck_mark_initialized(ptr, size);
19 BUG_ON(!valid_dma_direction(dir));
20 addr = ops->map_page(dev, virt_to_page(ptr),
21 (unsigned long)ptr & ~PAGE_MASK, size,
22 dir, attrs);
<Prasad> using the virt_to_page for the high memory will end up with
wrong address.
23 debug_dma_map_page(dev, virt_to_page(ptr),
24 (unsigned long)ptr & ~PAGE_MASK, size,
25 dir, addr, true);
26 return addr;
27 }
The only restriction which is observed that, ptr should point to
physically contiguous memory.
So can we pass high memory mapped address to dma_map_single API or not?
-Thanks, Prasad
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
Forum,
Linux Foundation Collaborative Project
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Query] doubt on parameters passed to dma_map_single_attrs() API
@ 2016-03-22 10:23 ` Sodagudi Prasad
0 siblings, 0 replies; 4+ messages in thread
From: Sodagudi Prasad @ 2016-03-22 10:23 UTC (permalink / raw)
To: linux-arm-kernel
Hi All,
Would like to check whether the dma_map_single_attrs() API, can accept
ptr variable from high memory or not?
If we pass the memory pointer, which is pointing high memory does not
work with virt_to_page API.
10 static inline dma_addr_t dma_map_single_attrs(struct device *dev,
void *ptr,
11 size_t size,
12 enum
dma_data_direction dir,
13 struct dma_attrs
*attrs)
14 {
15 const struct dma_map_ops *ops = get_dma_ops(dev);
16 dma_addr_t addr;
17
18 kmemcheck_mark_initialized(ptr, size);
19 BUG_ON(!valid_dma_direction(dir));
20 addr = ops->map_page(dev, virt_to_page(ptr),
21 (unsigned long)ptr & ~PAGE_MASK, size,
22 dir, attrs);
<Prasad> using the virt_to_page for the high memory will end up with
wrong address.
23 debug_dma_map_page(dev, virt_to_page(ptr),
24 (unsigned long)ptr & ~PAGE_MASK, size,
25 dir, addr, true);
26 return addr;
27 }
The only restriction which is observed that, ptr should point to
physically contiguous memory.
So can we pass high memory mapped address to dma_map_single API or not?
-Thanks, Prasad
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
Forum,
Linux Foundation Collaborative Project
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Query] doubt on parameters passed to dma_map_single_attrs() API
2016-03-22 10:23 ` Sodagudi Prasad
@ 2016-03-22 12:34 ` Russell King - ARM Linux
-1 siblings, 0 replies; 4+ messages in thread
From: Russell King - ARM Linux @ 2016-03-22 12:34 UTC (permalink / raw)
To: Sodagudi Prasad; +Cc: linux-kernel, linux-arm-kernel, shashim, sboyd
On Tue, Mar 22, 2016 at 03:53:02PM +0530, Sodagudi Prasad wrote:
>
> Hi All,
>
> Would like to check whether the dma_map_single_attrs() API, can accept ptr
> variable from high memory or not?
It can't. Direct mapped, lowmem only.
No pointers allowed from dma_alloc_coherent(), dma_alloc_writecombine(),
ioremap(), vmalloc(), kmap(), kmap_atomic() or similar function, or
derived from one of these.
--
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Query] doubt on parameters passed to dma_map_single_attrs() API
@ 2016-03-22 12:34 ` Russell King - ARM Linux
0 siblings, 0 replies; 4+ messages in thread
From: Russell King - ARM Linux @ 2016-03-22 12:34 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, Mar 22, 2016 at 03:53:02PM +0530, Sodagudi Prasad wrote:
>
> Hi All,
>
> Would like to check whether the dma_map_single_attrs() API, can accept ptr
> variable from high memory or not?
It can't. Direct mapped, lowmem only.
No pointers allowed from dma_alloc_coherent(), dma_alloc_writecombine(),
ioremap(), vmalloc(), kmap(), kmap_atomic() or similar function, or
derived from one of these.
--
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2016-03-22 12:34 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2016-03-22 10:23 [Query] doubt on parameters passed to dma_map_single_attrs() API Sodagudi Prasad
2016-03-22 10:23 ` Sodagudi Prasad
2016-03-22 12:34 ` Russell King - ARM Linux
2016-03-22 12:34 ` Russell King - ARM Linux
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