[PATCH v3 0/8] arm64: Default to 32-bit wide ZONE_DMA

[PATCH v3 0/8] arm64: Default to 32-bit wide ZONE_DMA

[Nicolas Saenz Julienne]

Using two distinct DMA zones turned out to be problematic. Here's an
attempt go back to a saner default.

I tested this on both a RPi4 and QEMU.

---

Changes since v2:
 - Introduce Ard's patch
 - Improve OF dma-ranges parsing function
 - Add unit test for OF function
 - Address small changes
 - Move crashkernel reservation later in boot process

Changes since v1:
 - Parse dma-ranges instead of using machine compatible string

Ard Biesheuvel (1):
  arm64: mm: Set ZONE_DMA size based on early IORT scan

Nicolas Saenz Julienne (7):
  arm64: mm: Move reserve_crashkernel() into mem_init()
  arm64: mm: Move zone_dma_bits initialization into zone_sizes_init()
  of/address: Introduce of_dma_get_max_cpu_address()
  of: unittest: Add test for of_dma_get_max_cpu_address()
  dma-direct: Turn zone_dma_bits default value into a define
  arm64: mm: Set ZONE_DMA size based on devicetree's dma-ranges
  mm: Update DMA zones description

 arch/arm64/include/asm/processor.h |  1 +
 arch/arm64/mm/init.c               | 20 ++++++------
 drivers/acpi/arm64/iort.c          | 51 ++++++++++++++++++++++++++++++
 drivers/of/address.c               | 42 ++++++++++++++++++++++++
 drivers/of/unittest.c              | 20 ++++++++++++
 include/linux/acpi_iort.h          |  4 +++
 include/linux/dma-direct.h         |  3 ++
 include/linux/mmzone.h             |  5 +--
 include/linux/of.h                 |  7 ++++
 kernel/dma/direct.c                |  2 +-
 10 files changed, 143 insertions(+), 12 deletions(-)

-- 
2.28.0

[PATCH v3 8/8] mm: Update DMA zones description

[Nicolas Saenz Julienne]

The default behavior for arm64 changed, so reflect that.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
---
 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

Re: [PATCH v3 8/8] mm: Update DMA zones description

[Christoph Hellwig]

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 <nsaenzjulienne@suse.de>
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> ---
>  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.