arm64 uses both ZONE_DMA and ZONE_DMA32 for the same reasons x86_64
does: peripherals with different DMA addressing limitations. This
updates both ZONE_DMAs comments to inform about the usage.
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx>
---
include/linux/mmzone.h | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index d77d717c620c..8fa6bcf72e7c 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -365,23 +365,24 @@ enum zone_type {
*
* Some examples
*
- * Architecture Limit
- * ---------------------------
- * parisc, ia64, sparc <4G
- * s390, powerpc <2G
- * arm Various
- * alpha Unlimited or 0-16MB.
+ * Architecture Limit
+ * ----------------------------------
+ * parisc, ia64, sparc, arm64 <4G
+ * s390, powerpc <2G
+ * arm Various
+ * alpha Unlimited or 0-16MB.
*
* i386, x86_64 and multiple other arches
- * <16M.
+ * <16M.
*/
ZONE_DMA,
#endif
#ifdef CONFIG_ZONE_DMA32
/*
- * x86_64 needs two ZONE_DMAs because it supports devices that are
- * only able to do DMA to the lower 16M but also 32 bit devices that
- * can only do DMA areas below 4G.
+ * x86_64 and arm64 need two ZONE_DMAs because they support devices
+ * that are only able to DMA a fraction of the 32 bit addressable
+ * memory area, but also devices that are limited to that whole 32 bit
+ * area.
*/
ZONE_DMA32,
#endif
--
2.22.0
