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[3/3] powerpc/dma: Remove ZONE_DMA completely

Message ID 87zj7amlqn.fsf@linux.vnet.ibm.com (mailing list archive)
State Not Applicable
Delegated to: Benjamin Herrenschmidt
Headers show

Commit Message

Aneesh Kumar K.V March 18, 2015, 2:19 p.m. UTC 
Benjamin Herrenschmidt <benh@kernel.crashing.org> writes:

> We don't initialize it, we don't use it, remove it.
>
> We can bring it back if we ever wish to have support for devices
> who have smaller than 32-bit DMA limitations but I don't think
> we care much anymore.
>
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> ---
>  arch/powerpc/Kconfig      |    2 +-
>  arch/powerpc/kernel/dma.c |   10 +---------
>  2 files changed, 2 insertions(+), 10 deletions(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 22b0940..4efbfba 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -712,7 +712,7 @@ config ISA
>  
>  config ZONE_DMA
>  	bool
> -	default y
> +	default n
>  
>  config NEED_DMA_MAP_STATE
>  	def_bool (PPC64 || NOT_COHERENT_CACHE)
> diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
> index e24e0ae..6306d4e 100644
> --- a/arch/powerpc/kernel/dma.c
> +++ b/arch/powerpc/kernel/dma.c
> @@ -63,16 +63,8 @@ void *dma_direct_alloc_coherent(struct device *dev, size_t size,
>  		return NULL;
>  	}
>  
> -	switch (zone) {
> -	case ZONE_DMA:
> -		flag |= GFP_DMA;
> -		break;
> -#ifdef CONFIG_ZONE_DMA32
> -	case ZONE_DMA32:
> +	if (zone == ZONE_DMA32)
>  		flag |= GFP_DMA32;
> -		break;
> -#endif
> -	};
>  

Why not do it also for DMA32 as below. We call limit_zone_pfn() only for few
platforms. They can select ZONE_DMA32. Everywhere else ZONE_DMA32 is
same as ZONE_NORMAL ? So instead of having confusing output for
show_mem(), we now have


Node 0 Normal: 6*64kB (UM) 566*128kB (UEM) 367*256kB (UM) 185*512kB (UM)59*1024kB (UEM) 11*2048kB (UM) 4*4096kB (UM) 3*8192kB (UEM) 4016*16384kB

Node 1 Normal: 42*64kB (UEM) 14*128kB (UEM) 10*256kB (UM) 2*512kB (UM) 6*1024kB (UM) 7*2048kB (UEM) 5*4096kB (UM) 2*8192kB (U) 3644*16384kB (MR) =

Comments

Benjamin Herrenschmidt March 18, 2015, 8:38 p.m. UTC | #1 
On Wed, 2015-03-18 at 19:49 +0530, Aneesh Kumar K.V wrote:
> Why not do it also for DMA32 as below. We call limit_zone_pfn() only
> for few
> platforms. They can select ZONE_DMA32. Everywhere else ZONE_DMA32 is
> same as ZONE_NORMAL ? So instead of having confusing output for
> show_mem(), we now have

There may be cases where we want ZONE_DMA32, what's confusing ?

Ben.
Aneesh Kumar K.V March 20, 2015, 5:26 a.m. UTC | #2 
Benjamin Herrenschmidt <benh@kernel.crashing.org> writes:

> On Wed, 2015-03-18 at 19:49 +0530, Aneesh Kumar K.V wrote:
>> Why not do it also for DMA32 as below. We call limit_zone_pfn() only
>> for few
>> platforms. They can select ZONE_DMA32. Everywhere else ZONE_DMA32 is
>> same as ZONE_NORMAL ? So instead of having confusing output for
>> show_mem(), we now have
>
> There may be cases where we want ZONE_DMA32, what's confusing ?
>
To see output like below

 Node 0 DMA32: 6*64kB (UM) 566*128kB (UEM) 367*256kB (UM) 185*512kB (UM)59*1024kB (UEM) 11*2048kB (UM) 4*4096kB (UM) 3*8192kB (UEM) 4016*16384kB

 Node 1 DMA32: 42*64kB (UEM) 14*128kB (UEM) 10*256kB (UM) 2*512kB (UM) 6*1024kB (UM) 7*2048kB (UEM) 5*4096kB (UM) 2*8192kB (U) 3644*16384kB (MR) =

 That is to find DMA32 convering more than 4GB range.

 -aneesh
diff mbox

Patch

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 38fe9c5409be..3a448cdaa22f 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -290,7 +290,7 @@  config PPC_EMULATE_SSTEP
 
 config ZONE_DMA32
 	bool
-	default y if PPC64
+	default n
 
 source "init/Kconfig"
 
diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index 03511968a9c6..253222ddb308 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -71,6 +71,11 @@  void *dma_direct_alloc_coherent(struct device *dev, size_t size,
 	}
 
 	switch (zone) {
+#ifdef CONFIG_ZONE_DMA
+	case ZONE_DMA:
+		flag |= GFP_DMA;
+		break;
+#endif
 #ifdef CONFIG_ZONE_DMA32
 	case ZONE_DMA32:
 		flag |= GFP_DMA32;