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[3/3] ARM: Fix DMA-bounce code to allow sync from_device and to_device with bidirectional mappings.

Message ID m338i9iwa6.fsf@intrepid.localdomain (mailing list archive)
State New, archived
Headers show

Commit Message

Krzysztof Halasa March 23, 2014, 12:38 a.m. UTC
This is equivalent of a more generic change to lib/dma-debug.c which is
present since v2.6.33:

commit 42d53b4ff7d61487d18274ebdf1f70c1aef6f122
dma-debug: allow DMA_BIDIRECTIONAL mappings to be synced with DMA_FROM_DEVICE
and DMA_TO_DEVICE.

There is no need to perform full BIDIR sync (copying the buffers in case
of swiotlb and similar schemes) if we know that the owner (CPU or device)
hasn't altered the data.

Addresses the false-positive reported at
http://bugzilla.kernel.org/show_bug.cgi?id=14169

Signed-off-by: Krzysztof Ha?asa <khc@pm.waw.pl>

Comments

Simon Kagstrom March 24, 2014, 1:51 p.m. UTC | #1
On Sun, 23 Mar 2014 01:38:41 +0100
Krzysztof Halasa <khc@pm.waw.pl> wrote:

> This is equivalent of a more generic change to lib/dma-debug.c which is
> present since v2.6.33:
> 
> commit 42d53b4ff7d61487d18274ebdf1f70c1aef6f122
> dma-debug: allow DMA_BIDIRECTIONAL mappings to be synced with DMA_FROM_DEVICE
> and DMA_TO_DEVICE.
> 
> There is no need to perform full BIDIR sync (copying the buffers in case
> of swiotlb and similar schemes) if we know that the owner (CPU or device)
> hasn't altered the data.
> 
> Addresses the false-positive reported at
> http://bugzilla.kernel.org/show_bug.cgi?id=14169
> 
> Signed-off-by: Krzysztof Ha?asa <khc@pm.waw.pl>

Tested-by: Simon Kagstrom <simon.kagstrom@netinsight.net>

(Tested with a e100 device which previously triggered this).

// Simon
Arnd Bergmann March 26, 2014, 10:10 p.m. UTC | #2
On Sunday 23 March 2014, Krzysztof Halasa wrote:
> This is equivalent of a more generic change to lib/dma-debug.c which is
> present since v2.6.33:
> 
> commit 42d53b4ff7d61487d18274ebdf1f70c1aef6f122
> dma-debug: allow DMA_BIDIRECTIONAL mappings to be synced with DMA_FROM_DEVICE
> and DMA_TO_DEVICE.
> 
> There is no need to perform full BIDIR sync (copying the buffers in case
> of swiotlb and similar schemes) if we know that the owner (CPU or device)
> hasn't altered the data.
> 
> Addresses the false-positive reported at
> http://bugzilla.kernel.org/show_bug.cgi?id=14169
> 
> Signed-off-by: Krzysztof Ha?asa <khc@pm.waw.pl>

Looks good to me. Can you add it to Russell's patch tracker?

Acked-by: Arnd Bergmann <arnd@arndb.de>

	Arnd

> diff --git a/arch/arm/common/dmabounce.c b/arch/arm/common/dmabounce.c
> index 1143c4d..b4c17cf 100644
> --- a/arch/arm/common/dmabounce.c
> +++ b/arch/arm/common/dmabounce.c
> @@ -375,7 +375,7 @@ static int __dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
>  
>  	off = addr - buf->safe_dma_addr;
>  
> -	BUG_ON(buf->direction != dir);
> +	BUG_ON(buf->direction != dir && buf->direction != DMA_BIDIRECTIONAL);
>  
>  	dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n",
>  		__func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,
> @@ -415,7 +415,7 @@ static int __dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
>  
>  	off = addr - buf->safe_dma_addr;
>  
> -	BUG_ON(buf->direction != dir);
> +	BUG_ON(buf->direction != dir && buf->direction != DMA_BIDIRECTIONAL);
>  
>  	dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n",
>  		__func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,
>
diff mbox

Patch

diff --git a/arch/arm/common/dmabounce.c b/arch/arm/common/dmabounce.c
index 1143c4d..b4c17cf 100644
--- a/arch/arm/common/dmabounce.c
+++ b/arch/arm/common/dmabounce.c
@@ -375,7 +375,7 @@  static int __dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
 
 	off = addr - buf->safe_dma_addr;
 
-	BUG_ON(buf->direction != dir);
+	BUG_ON(buf->direction != dir && buf->direction != DMA_BIDIRECTIONAL);
 
 	dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n",
 		__func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,
@@ -415,7 +415,7 @@  static int __dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
 
 	off = addr - buf->safe_dma_addr;
 
-	BUG_ON(buf->direction != dir);
+	BUG_ON(buf->direction != dir && buf->direction != DMA_BIDIRECTIONAL);
 
 	dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n",
 		__func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,