[PATCH v4.4] net: davinci_cpdma: use dma_addr_t for DMA address

[PATCH v4.4] net: davinci_cpdma: use dma_addr_t for DMA address

[Daniel Wagner]

From: Arnd Bergmann <arnd@arndb.de>

[ Upstream commit 84092996673211f16ef3b942a191d7952e9dfea9 ]

The davinci_cpdma mixes up physical addresses as seen from the CPU
and DMA addresses as seen from a DMA master, since it can operate
on both normal memory or an on-chip buffer. If dma_addr_t is
different from phys_addr_t, this means we get a compile-time warning
about the type mismatch:

ethernet/ti/davinci_cpdma.c: In function 'cpdma_desc_pool_create':
ethernet/ti/davinci_cpdma.c:182:48: error: passing argument 3 of 'dma_alloc_coherent' from incompatible pointer type [-Werror=incompatible-pointer-types]
   pool->cpumap = dma_alloc_coherent(dev, size, &pool->phys,
In file included from ethernet/ti/davinci_cpdma.c:21:0:
dma-mapping.h:398:21: note: expected 'dma_addr_t * {aka long long unsigned int *}' but argument is of type 'phys_addr_t * {aka unsigned int *}'
 static inline void *dma_alloc_coherent(struct device *dev, size_t size,

This slightly restructures the code so the address we use for
mapping RAM into a DMA address is always a dma_addr_t, avoiding
the warning. The code is correct even if both types are 32-bit
because the DMA master in this device only supports 32-bit addressing
anyway, independent of the types that are used.

We still assign this value to pool->phys, and that is wrong if
the driver is ever used with an IOMMU, but that value appears to
be never used, so there is no problem really. I've added a couple
of comments about where we do things that are slightly violating
the API.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
---

Hi,

Pavel reported this fix is needed for the CIP kernel.

Since this patch was added to v4.5, we only need to backport
to v4.4.

Thanks,
Daniel

 drivers/net/ethernet/ti/davinci_cpdma.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/ti/davinci_cpdma.c b/drivers/net/ethernet/ti/davinci_cpdma.c
index 657b65bf5cac..18bf3a8fdc50 100644
--- a/drivers/net/ethernet/ti/davinci_cpdma.c
+++ b/drivers/net/ethernet/ti/davinci_cpdma.c
@@ -82,7 +82,7 @@ struct cpdma_desc {
 
 struct cpdma_desc_pool {
 	phys_addr_t		phys;
-	u32			hw_addr;
+	dma_addr_t		hw_addr;
 	void __iomem		*iomap;		/* ioremap map */
 	void			*cpumap;	/* dma_alloc map */
 	int			desc_size, mem_size;
@@ -152,7 +152,7 @@ struct cpdma_chan {
  * abstract out these details
  */
 static struct cpdma_desc_pool *
-cpdma_desc_pool_create(struct device *dev, u32 phys, u32 hw_addr,
+cpdma_desc_pool_create(struct device *dev, u32 phys, dma_addr_t hw_addr,
 				int size, int align)
 {
 	int bitmap_size;
@@ -176,13 +176,13 @@ cpdma_desc_pool_create(struct device *dev, u32 phys, u32 hw_addr,
 
 	if (phys) {
 		pool->phys  = phys;
-		pool->iomap = ioremap(phys, size);
+		pool->iomap = ioremap(phys, size); /* should be memremap? */
 		pool->hw_addr = hw_addr;
 	} else {
-		pool->cpumap = dma_alloc_coherent(dev, size, &pool->phys,
+		pool->cpumap = dma_alloc_coherent(dev, size, &pool->hw_addr,
 						  GFP_KERNEL);
-		pool->iomap = pool->cpumap;
-		pool->hw_addr = pool->phys;
+		pool->iomap = (void __iomem __force *)pool->cpumap;
+		pool->phys = pool->hw_addr; /* assumes no IOMMU, don't use this value */
 	}
 
 	if (pool->iomap)
-- 
2.24.0

Re: [PATCH v4.4] net: davinci_cpdma: use dma_addr_t for DMA address

[Greg KH]

On Sat, Dec 21, 2019 at 11:49:48AM +0100, Daniel Wagner wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> [ Upstream commit 84092996673211f16ef3b942a191d7952e9dfea9 ]
> 
> The davinci_cpdma mixes up physical addresses as seen from the CPU
> and DMA addresses as seen from a DMA master, since it can operate
> on both normal memory or an on-chip buffer. If dma_addr_t is
> different from phys_addr_t, this means we get a compile-time warning
> about the type mismatch:
> 
> ethernet/ti/davinci_cpdma.c: In function 'cpdma_desc_pool_create':
> ethernet/ti/davinci_cpdma.c:182:48: error: passing argument 3 of 'dma_alloc_coherent' from incompatible pointer type [-Werror=incompatible-pointer-types]
>    pool->cpumap = dma_alloc_coherent(dev, size, &pool->phys,
> In file included from ethernet/ti/davinci_cpdma.c:21:0:
> dma-mapping.h:398:21: note: expected 'dma_addr_t * {aka long long unsigned int *}' but argument is of type 'phys_addr_t * {aka unsigned int *}'
>  static inline void *dma_alloc_coherent(struct device *dev, size_t size,
> 
> This slightly restructures the code so the address we use for
> mapping RAM into a DMA address is always a dma_addr_t, avoiding
> the warning. The code is correct even if both types are 32-bit
> because the DMA master in this device only supports 32-bit addressing
> anyway, independent of the types that are used.
> 
> We still assign this value to pool->phys, and that is wrong if
> the driver is ever used with an IOMMU, but that value appears to
> be never used, so there is no problem really. I've added a couple
> of comments about where we do things that are slightly violating
> the API.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: David S. Miller <davem@davemloft.net>
> Signed-off-by: Daniel Wagner <dwagner@suse.de>
> ---
> 
> Hi,
> 
> Pavel reported this fix is needed for the CIP kernel.
> 
> Since this patch was added to v4.5, we only need to backport
> to v4.4.

Now queued up, thanks.

greg k-h

Re: [PATCH v4.4] net: davinci_cpdma: use dma_addr_t for DMA address

[Ben Hutchings]

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On Sat, 2019-12-21 at 11:49 +0100, Daniel Wagner wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> [ Upstream commit 84092996673211f16ef3b942a191d7952e9dfea9 ]
[...]
> Pavel reported this fix is needed for the CIP kernel.
> 
> Since this patch was added to v4.5, we only need to backport
> to v4.4.

It looks like it's also applicable to 3.16, so I've queued it up for
that.

Ben.

> Thanks,
> Daniel
> 
>  drivers/net/ethernet/ti/davinci_cpdma.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/ethernet/ti/davinci_cpdma.c b/drivers/net/ethernet/ti/davinci_cpdma.c
> index 657b65bf5cac..18bf3a8fdc50 100644
> --- a/drivers/net/ethernet/ti/davinci_cpdma.c
> +++ b/drivers/net/ethernet/ti/davinci_cpdma.c
> @@ -82,7 +82,7 @@ struct cpdma_desc {
>  
>  struct cpdma_desc_pool {
>  	phys_addr_t		phys;
> -	u32			hw_addr;
> +	dma_addr_t		hw_addr;
>  	void __iomem		*iomap;		/* ioremap map */
>  	void			*cpumap;	/* dma_alloc map */
>  	int			desc_size, mem_size;
> @@ -152,7 +152,7 @@ struct cpdma_chan {
>   * abstract out these details
>   */
>  static struct cpdma_desc_pool *
> -cpdma_desc_pool_create(struct device *dev, u32 phys, u32 hw_addr,
> +cpdma_desc_pool_create(struct device *dev, u32 phys, dma_addr_t hw_addr,
>  				int size, int align)
>  {
>  	int bitmap_size;
> @@ -176,13 +176,13 @@ cpdma_desc_pool_create(struct device *dev, u32 phys, u32 hw_addr,
>  
>  	if (phys) {
>  		pool->phys  = phys;
> -		pool->iomap = ioremap(phys, size);
> +		pool->iomap = ioremap(phys, size); /* should be memremap? */
>  		pool->hw_addr = hw_addr;
>  	} else {
> -		pool->cpumap = dma_alloc_coherent(dev, size, &pool->phys,
> +		pool->cpumap = dma_alloc_coherent(dev, size, &pool->hw_addr,
>  						  GFP_KERNEL);
> -		pool->iomap = pool->cpumap;
> -		pool->hw_addr = pool->phys;
> +		pool->iomap = (void __iomem __force *)pool->cpumap;
> +		pool->phys = pool->hw_addr; /* assumes no IOMMU, don't use this value */
>  	}
>  
>  	if (pool->iomap)
-- 
Ben Hutchings
The program is absolutely right; therefore, the computer must be wrong.



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Re: [PATCH v4.4] net: davinci_cpdma: use dma_addr_t for DMA address

[Daniel Wagner]

Hi Ben,

On 26.01.20 18:36, Ben Hutchings wrote:
> On Sat, 2019-12-21 at 11:49 +0100, Daniel Wagner wrote:
>> From: Arnd Bergmann <arnd@arndb.de>
>>
>> [ Upstream commit 84092996673211f16ef3b942a191d7952e9dfea9 ]
> [...]
>> Pavel reported this fix is needed for the CIP kernel.
>>
>> Since this patch was added to v4.5, we only need to backport
>> to v4.4.
> 
> It looks like it's also applicable to 3.16, so I've queued it up for
> that.

Oh sorry, I forgot to check if 3.16 needs it. I had the impression 3.16 
was already EOL. Obviously, still alive :)

Thanks,
Daniel