[patch 2.6.28-rc5] SPI -- Freescale iMX SPI controller driver

[patch 2.6.28-rc5] SPI -- Freescale iMX SPI controller driver

[Andrea Paterniani]

Subject: [patch-2.6.28-rc5-spi_imx] arm: SPI controller driver for 
Freescale iMX
From: Andrea Paterniani <a.paterniani@swapp-eng.it>

Kernel version: linux-2.6.28-rc5.
Patch description:
Fix unsafe order in dma mapping operation.

Signed-off-by: Andrea Paterniani <a.paterniani@swapp-eng.it>
---

diff -uprN -X linux-2.6.28-rc5/Documentation/dontdiff 
linux-2.6.28-rc5/drivers/spi/spi_imx.c 
linux-2.6.28-rc5-spi_imx/drivers/spi/spi_imx.c
--- linux-2.6.28-rc5/drivers/spi/spi_imx.c    2008-10-10 
00:13:53.000000000 +0200
+++ linux-2.6.28-rc5-spi_imx/drivers/spi/spi_imx.c    2008-11-17 
11:26:54.000000000 +0100
@@ -506,20 +506,6 @@ static int map_dma_buffers(struct driver
     if (!IS_DMA_ALIGNED(drv_data->rx) || !IS_DMA_ALIGNED(drv_data->tx))
         return -1;
 
-    /* NULL rx means write-only transfer and no map needed
-       since rx DMA will not be used */
-    if (drv_data->rx) {
-        buf = drv_data->rx;
-        drv_data->rx_dma = dma_map_single(
-                    dev,
-                    buf,
-                    drv_data->len,
-                    DMA_FROM_DEVICE);
-        if (dma_mapping_error(dev, drv_data->rx_dma))
-            return -1;
-        drv_data->rx_dma_needs_unmap = 1;
-    }
-
     if (drv_data->tx == NULL) {
         /* Read only message --> use drv_data->dummy_dma_buf for dummy
            writes to achive reads */
@@ -533,18 +519,31 @@ static int map_dma_buffers(struct driver
                     buf,
                     drv_data->tx_map_len,
                     DMA_TO_DEVICE);
-    if (dma_mapping_error(dev, drv_data->tx_dma)) {
-        if (drv_data->rx_dma) {
-            dma_unmap_single(dev,
-                    drv_data->rx_dma,
-                    drv_data->len,
-                    DMA_FROM_DEVICE);
-            drv_data->rx_dma_needs_unmap = 0;
-        }
+    if (dma_mapping_error(dev, drv_data->tx_dma))
         return -1;
-    }
     drv_data->tx_dma_needs_unmap = 1;
 
+    /* NULL rx means write-only transfer and no map needed
+       since rx DMA will not be used */
+    if (drv_data->rx) {
+        buf = drv_data->rx;
+        drv_data->rx_dma = dma_map_single(dev,
+                        buf,
+                        drv_data->len,
+                        DMA_FROM_DEVICE);
+        if (dma_mapping_error(dev, drv_data->rx_dma)) {
+            if (drv_data->tx_dma) {
+                dma_unmap_single(dev,
+                        drv_data->tx_dma,
+                        drv_data->tx_map_len,
+                        DMA_TO_DEVICE);
+                drv_data->tx_dma_needs_unmap = 0;
+            }
+            return -1;
+        }
+        drv_data->rx_dma_needs_unmap = 1;
+    }
+
     return 0;
 }
 

-- 

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Re: [patch 2.6.28-rc5] SPI -- Freescale iMX SPI controller driver

[David Brownell]

On Monday 17 November 2008, Andrea Paterniani wrote:
> Fix unsafe order in dma mapping operation.

This arrived horribly mangled.  Can you verify that the
appended patch is an appropriate un-mangled version?

======= CUT HERE
From: Andrea Paterniani <a.paterniani-03BXCEkGbFHYGGNLXY5/rw@public.gmane.org>

Fix unsafe order in dma mapping operation: always flush data from
the cache *BEFORE* invalidating it, to allow full duplex transfers
where the same buffer may be used for both writes and reads.

Signed-off-by: Andrea Paterniani <a.paterniani-03BXCEkGbFHYGGNLXY5/rw@public.gmane.org>
---
 drivers/spi/spi_imx.c |   45 ++++++++++++++++++++++-----------------------
 1 file changed, 22 insertions(+), 23 deletions(-)

--- a/drivers/spi/spi_imx.c
+++ b/drivers/spi/spi_imx.c
@@ -506,20 +506,6 @@ static int map_dma_buffers(struct driver
 	if (!IS_DMA_ALIGNED(drv_data->rx) || !IS_DMA_ALIGNED(drv_data->tx))
 		return -1;
 
-	/* NULL rx means write-only transfer and no map needed
-	   since rx DMA will not be used */
-	if (drv_data->rx) {
-		buf = drv_data->rx;
-		drv_data->rx_dma = dma_map_single(
-					dev,
-					buf,
-					drv_data->len,
-					DMA_FROM_DEVICE);
-		if (dma_mapping_error(dev, drv_data->rx_dma))
-			return -1;
-		drv_data->rx_dma_needs_unmap = 1;
-	}
-
 	if (drv_data->tx == NULL) {
 		/* Read only message --> use drv_data->dummy_dma_buf for dummy
 		   writes to achive reads */
@@ -533,18 +519,31 @@ static int map_dma_buffers(struct driver
 					buf,
 					drv_data->tx_map_len,
 					DMA_TO_DEVICE);
-	if (dma_mapping_error(dev, drv_data->tx_dma)) {
-		if (drv_data->rx_dma) {
-			dma_unmap_single(dev,
-					drv_data->rx_dma,
-					drv_data->len,
-					DMA_FROM_DEVICE);
-			drv_data->rx_dma_needs_unmap = 0;
-		}
+	if (dma_mapping_error(dev, drv_data->tx_dma))
 		return -1;
-	}
 	drv_data->tx_dma_needs_unmap = 1;
 
+	/* NULL rx means write-only transfer and no map needed
+	 * since rx DMA will not be used */
+	if (drv_data->rx) {
+		buf = drv_data->rx;
+		drv_data->rx_dma = dma_map_single(dev,
+						buf,
+						drv_data->len,
+						DMA_FROM_DEVICE);
+		if (dma_mapping_error(dev, drv_data->rx_dma)) {
+			if (drv_data->tx_dma) {
+				dma_unmap_single(dev,
+						drv_data->tx_dma,
+						drv_data->tx_map_len,
+						DMA_TO_DEVICE);
+				drv_data->tx_dma_needs_unmap = 0;
+			}
+			return -1;
+		}
+		drv_data->rx_dma_needs_unmap = 1;
+	}
+
 	return 0;
 }
 


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Re: [patch 2.6.28-rc5] SPI -- Freescale iMX SPI controller driver

[Andrea Paterniani]

[-- Attachment #1.1: Type: text/plain, Size: 3364 bytes --]

It's ok.
The only difference I see is a character * added a the beginning of a 
comment:

+	/* NULL rx means write-only transfer and no map needed
+	 * since rx DMA will not be used */

should be

+	/* NULL rx means write-only transfer and no map needed
+	   since rx DMA will not be used */


Regards,
- Andrea


David Brownell ha scritto:
> On Monday 17 November 2008, Andrea Paterniani wrote:
>   
>> Fix unsafe order in dma mapping operation.
>>     
>
> This arrived horribly mangled.  Can you verify that the
> appended patch is an appropriate un-mangled version?
>
> ======= CUT HERE
> From: Andrea Paterniani <a.paterniani-03BXCEkGbFHYGGNLXY5/rw@public.gmane.org>
>
> Fix unsafe order in dma mapping operation: always flush data from
> the cache *BEFORE* invalidating it, to allow full duplex transfers
> where the same buffer may be used for both writes and reads.
>
> Signed-off-by: Andrea Paterniani <a.paterniani-03BXCEkGbFHYGGNLXY5/rw@public.gmane.org>
> ---
>  drivers/spi/spi_imx.c |   45 ++++++++++++++++++++++-----------------------
>  1 file changed, 22 insertions(+), 23 deletions(-)
>
> --- a/drivers/spi/spi_imx.c
> +++ b/drivers/spi/spi_imx.c
> @@ -506,20 +506,6 @@ static int map_dma_buffers(struct driver
>  	if (!IS_DMA_ALIGNED(drv_data->rx) || !IS_DMA_ALIGNED(drv_data->tx))
>  		return -1;
>  
> -	/* NULL rx means write-only transfer and no map needed
> -	   since rx DMA will not be used */
> -	if (drv_data->rx) {
> -		buf = drv_data->rx;
> -		drv_data->rx_dma = dma_map_single(
> -					dev,
> -					buf,
> -					drv_data->len,
> -					DMA_FROM_DEVICE);
> -		if (dma_mapping_error(dev, drv_data->rx_dma))
> -			return -1;
> -		drv_data->rx_dma_needs_unmap = 1;
> -	}
> -
>  	if (drv_data->tx == NULL) {
>  		/* Read only message --> use drv_data->dummy_dma_buf for dummy
>  		   writes to achive reads */
> @@ -533,18 +519,31 @@ static int map_dma_buffers(struct driver
>  					buf,
>  					drv_data->tx_map_len,
>  					DMA_TO_DEVICE);
> -	if (dma_mapping_error(dev, drv_data->tx_dma)) {
> -		if (drv_data->rx_dma) {
> -			dma_unmap_single(dev,
> -					drv_data->rx_dma,
> -					drv_data->len,
> -					DMA_FROM_DEVICE);
> -			drv_data->rx_dma_needs_unmap = 0;
> -		}
> +	if (dma_mapping_error(dev, drv_data->tx_dma))
>  		return -1;
> -	}
>  	drv_data->tx_dma_needs_unmap = 1;
>  
> +	/* NULL rx means write-only transfer and no map needed
> +	 * since rx DMA will not be used */
> +	if (drv_data->rx) {
> +		buf = drv_data->rx;
> +		drv_data->rx_dma = dma_map_single(dev,
> +						buf,
> +						drv_data->len,
> +						DMA_FROM_DEVICE);
> +		if (dma_mapping_error(dev, drv_data->rx_dma)) {
> +			if (drv_data->tx_dma) {
> +				dma_unmap_single(dev,
> +						drv_data->tx_dma,
> +						drv_data->tx_map_len,
> +						DMA_TO_DEVICE);
> +				drv_data->tx_dma_needs_unmap = 0;
> +			}
> +			return -1;
> +		}
> +		drv_data->rx_dma_needs_unmap = 1;
> +	}
> +
>  	return 0;
>  }
>  
>
>
>   

-- 


 

------------------------------------------------------------------------

*Ing. Andrea Paterniani*

*SWAPP* - Studio Professionale
Via degli Abeti, 312 - 61100 Pesaro
Tel 0721 24256
Fax 178 220 8730
 
a.paterniani-03BXCEkGbFHYGGNLXY5/rw@public.gmane.org
www.swapp-eng.it 
<mailto:%0d%0aa.paterniani-03BXCEkGbFHYGGNLXY5/rw@public.gmane.org%0d%0awww.swapp-eng.it>

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