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[PATCH 1/7] dma: Take into account dma_pfn_offset

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  [PATCH 1/7] dma: Take into account dma_pfn_offset Vladimir Murzin <vladimir.murzin@arm.com> - 2017-02-15 11:10 +0100
    Re: [PATCH 1/7] dma: Take into account dma_pfn_offset Robin Murphy <robin.murphy@arm.com> - 2017-02-21 14:10 +0100
      Re: [PATCH 1/7] dma: Take into account dma_pfn_offset Vladimir Murzin <vladimir.murzin@arm.com> - 2017-02-21 14:30 +0100

#1581179 — [PATCH 1/7] dma: Take into account dma_pfn_offset

Even though dma-noop-ops assumes 1:1 memory mapping DMA memory range
can be different to RAM. For example, ARM STM32F4 MCU offers the
possibility to remap SDRAM from 0xc000_0000 to 0x0 to get CPU
performance boost, but DMA continue to see SDRAM at 0xc000_0000. This
difference in mapping is handled via device-tree "dma-range" property
which leads to dev->dma_pfn_offset is set nonzero. To handle such
cases take dma_pfn_offset into account.

Cc: Joerg Roedel <jroedel@suse.de>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Reported-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Tested-by: Andras Szemzo <sza@esh.hu>
Tested-by: Alexandre TORGUE <alexandre.torgue@st.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
---
 lib/dma-noop.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/dma-noop.c b/lib/dma-noop.c
index 3d766e7..a14eee5 100644
--- a/lib/dma-noop.c
+++ b/lib/dma-noop.c
@@ -7,6 +7,7 @@
 #include <linux/mm.h>
 #include <linux/dma-mapping.h>
 #include <linux/scatterlist.h>
+#include <linux/pfn.h>
 
 static void *dma_noop_alloc(struct device *dev, size_t size,
 			    dma_addr_t *dma_handle, gfp_t gfp,
@@ -16,7 +17,8 @@ static void *dma_noop_alloc(struct device *dev, size_t size,
 
 	ret = (void *)__get_free_pages(gfp, get_order(size));
 	if (ret)
-		*dma_handle = virt_to_phys(ret);
+		*dma_handle = virt_to_phys(ret) - PFN_PHYS(dev->dma_pfn_offset);
+
 	return ret;
 }
 
@@ -32,7 +34,7 @@ static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page,
 				      enum dma_data_direction dir,
 				      unsigned long attrs)
 {
-	return page_to_phys(page) + offset;
+	return page_to_phys(page) + offset - PFN_PHYS(dev->dma_pfn_offset);
 }
 
 static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
@@ -47,7 +49,7 @@ static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nent
 
 		BUG_ON(!sg_page(sg));
 		va = sg_virt(sg);
-		sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va);
+		sg_dma_address(sg) = (dma_addr_t)(virt_to_phys(va) - PFN_PHYS(dev->dma_pfn_offset));
 		sg_dma_len(sg) = sg->length;
 	}
 
-- 
2.0.0

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#1585278

On 15/02/17 09:59, Vladimir Murzin wrote:
> Even though dma-noop-ops assumes 1:1 memory mapping DMA memory range
> can be different to RAM. For example, ARM STM32F4 MCU offers the
> possibility to remap SDRAM from 0xc000_0000 to 0x0 to get CPU
> performance boost, but DMA continue to see SDRAM at 0xc000_0000. This
> difference in mapping is handled via device-tree "dma-range" property
> which leads to dev->dma_pfn_offset is set nonzero. To handle such
> cases take dma_pfn_offset into account.

Modulo trivial style nits (include order, line length) which I'll leave
for others to object to if they wish, this looks correct to me.

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Cc: Joerg Roedel <jroedel@suse.de>
> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
> Reported-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
> Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
> Tested-by: Andras Szemzo <sza@esh.hu>
> Tested-by: Alexandre TORGUE <alexandre.torgue@st.com>
> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
> ---
>  lib/dma-noop.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/dma-noop.c b/lib/dma-noop.c
> index 3d766e7..a14eee5 100644
> --- a/lib/dma-noop.c
> +++ b/lib/dma-noop.c
> @@ -7,6 +7,7 @@
>  #include <linux/mm.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/scatterlist.h>
> +#include <linux/pfn.h>
>  
>  static void *dma_noop_alloc(struct device *dev, size_t size,
>  			    dma_addr_t *dma_handle, gfp_t gfp,
> @@ -16,7 +17,8 @@ static void *dma_noop_alloc(struct device *dev, size_t size,
>  
>  	ret = (void *)__get_free_pages(gfp, get_order(size));
>  	if (ret)
> -		*dma_handle = virt_to_phys(ret);
> +		*dma_handle = virt_to_phys(ret) - PFN_PHYS(dev->dma_pfn_offset);
> +
>  	return ret;
>  }
>  
> @@ -32,7 +34,7 @@ static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page,
>  				      enum dma_data_direction dir,
>  				      unsigned long attrs)
>  {
> -	return page_to_phys(page) + offset;
> +	return page_to_phys(page) + offset - PFN_PHYS(dev->dma_pfn_offset);
>  }
>  
>  static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
> @@ -47,7 +49,7 @@ static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nent
>  
>  		BUG_ON(!sg_page(sg));
>  		va = sg_virt(sg);
> -		sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va);
> +		sg_dma_address(sg) = (dma_addr_t)(virt_to_phys(va) - PFN_PHYS(dev->dma_pfn_offset));
>  		sg_dma_len(sg) = sg->length;
>  	}
>  
> 

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#1585331

On 21/02/17 13:07, Robin Murphy wrote:
> On 15/02/17 09:59, Vladimir Murzin wrote:
>> Even though dma-noop-ops assumes 1:1 memory mapping DMA memory range
>> can be different to RAM. For example, ARM STM32F4 MCU offers the
>> possibility to remap SDRAM from 0xc000_0000 to 0x0 to get CPU
>> performance boost, but DMA continue to see SDRAM at 0xc000_0000. This
>> difference in mapping is handled via device-tree "dma-range" property
>> which leads to dev->dma_pfn_offset is set nonzero. To handle such
>> cases take dma_pfn_offset into account.
> 
> Modulo trivial style nits (include order, line length) which I'll leave
> for others to object to if they wish, this looks correct to me.
> 
> Reviewed-by: Robin Murphy <robin.murphy@arm.com>

Much appreciated!

Vladimir

> 
>> Cc: Joerg Roedel <jroedel@suse.de>
>> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
>> Reported-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
>> Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
>> Tested-by: Andras Szemzo <sza@esh.hu>
>> Tested-by: Alexandre TORGUE <alexandre.torgue@st.com>
>> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
>> ---
>>  lib/dma-noop.c | 8 +++++---
>>  1 file changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/lib/dma-noop.c b/lib/dma-noop.c
>> index 3d766e7..a14eee5 100644
>> --- a/lib/dma-noop.c
>> +++ b/lib/dma-noop.c
>> @@ -7,6 +7,7 @@
>>  #include <linux/mm.h>
>>  #include <linux/dma-mapping.h>
>>  #include <linux/scatterlist.h>
>> +#include <linux/pfn.h>
>>  
>>  static void *dma_noop_alloc(struct device *dev, size_t size,
>>  			    dma_addr_t *dma_handle, gfp_t gfp,
>> @@ -16,7 +17,8 @@ static void *dma_noop_alloc(struct device *dev, size_t size,
>>  
>>  	ret = (void *)__get_free_pages(gfp, get_order(size));
>>  	if (ret)
>> -		*dma_handle = virt_to_phys(ret);
>> +		*dma_handle = virt_to_phys(ret) - PFN_PHYS(dev->dma_pfn_offset);
>> +
>>  	return ret;
>>  }
>>  
>> @@ -32,7 +34,7 @@ static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page,
>>  				      enum dma_data_direction dir,
>>  				      unsigned long attrs)
>>  {
>> -	return page_to_phys(page) + offset;
>> +	return page_to_phys(page) + offset - PFN_PHYS(dev->dma_pfn_offset);
>>  }
>>  
>>  static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
>> @@ -47,7 +49,7 @@ static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nent
>>  
>>  		BUG_ON(!sg_page(sg));
>>  		va = sg_virt(sg);
>> -		sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va);
>> +		sg_dma_address(sg) = (dma_addr_t)(virt_to_phys(va) - PFN_PHYS(dev->dma_pfn_offset));
>>  		sg_dma_len(sg) = sg->length;
>>  	}
>>  
>>
> 
> 

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