Re: [PATCH v3 8/8] mm: Update DMA zones description
On Wed, Oct 14, 2020 at 09:12:10PM +0200, Nicolas Saenz Julienne wrote:
> The default behavior for arm64 changed, so reflect that.
>
> Signed-off-by: Nicolas Saenz Julienne
> Acked-by: Catalin Marinas
> ---
> include/linux/mmzone.h | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index fb3bf696c05e..4ee2306351b9 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -363,8 +363,9 @@ enum zone_type {
>* - arm only uses ZONE_DMA, the size, up to 4G, may vary depending on
>*the specific device.
>*
> - * - arm64 has a fixed 1G ZONE_DMA and ZONE_DMA32 for the rest of the
> - *lower 4G.
> + * - arm64 uses a single 4GB ZONE_DMA, except on the Raspberry Pi 4,
> + *in which ZONE_DMA covers the first GB and ZONE_DMA32 the rest of
> + *the lower 4GB.
Honestly I think this comment just needs to go away. We can't really list
every setup in a comment in common code.
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[PATCH v3 8/8] mm: Update DMA zones description
The default behavior for arm64 changed, so reflect that.
Signed-off-by: Nicolas Saenz Julienne
Acked-by: Catalin Marinas
---
include/linux/mmzone.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index fb3bf696c05e..4ee2306351b9 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -363,8 +363,9 @@ enum zone_type {
* - arm only uses ZONE_DMA, the size, up to 4G, may vary depending on
*the specific device.
*
-* - arm64 has a fixed 1G ZONE_DMA and ZONE_DMA32 for the rest of the
-*lower 4G.
+* - arm64 uses a single 4GB ZONE_DMA, except on the Raspberry Pi 4,
+*in which ZONE_DMA covers the first GB and ZONE_DMA32 the rest of
+*the lower 4GB.
*
* - powerpc only uses ZONE_DMA, the size, up to 2G, may vary
*depending on the specific device.
--
2.28.0
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