[v5,0/7] arm64: Default to 32-bit wide ZONE_DMA

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 v4:
 - Fix of_dma_get_max_cpu_address() so it returns the last addressable
   addres, not the limit

Changes since v3:
 - Drop patch adding define in dma-mapping
 - Address small review changes
 - Update Ard's patch
 - Add new patch removing examples from mmzone.h

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 (6):
  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()
  arm64: mm: Set ZONE_DMA size based on devicetree's dma-ranges
  mm: Remove examples from enum zone_type comment

 arch/arm64/mm/init.c      | 16 ++++++------
 drivers/acpi/arm64/iort.c | 52 +++++++++++++++++++++++++++++++++++++++
 drivers/of/address.c      | 42 +++++++++++++++++++++++++++++++
 drivers/of/unittest.c     | 18 ++++++++++++++
 include/linux/acpi_iort.h |  4 +++
 include/linux/mmzone.h    | 20 ---------------
 include/linux/of.h        |  7 ++++++
 7 files changed, 130 insertions(+), 29 deletions(-)

On Thu, Oct 29, 2020 at 06:25:49PM +0100, Nicolas Saenz Julienne wrote:
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c

> index 9929ff50c0c0..05fe4a076bab 100644

> --- a/drivers/acpi/arm64/iort.c

> +++ b/drivers/acpi/arm64/iort.c

> @@ -1718,3 +1718,55 @@ void __init acpi_iort_init(void)

>  

>  	iort_init_platform_devices();

>  }

> +

> +#ifdef CONFIG_ZONE_DMA

> +/*

> + * Check the IORT whether any devices exist whose DMA mask is < 32 bits.

> + * If so, return the smallest value encountered, or 32 otherwise.

> + */

> +unsigned int __init acpi_iort_get_zone_dma_size(void)

> +{

> +	struct acpi_table_iort *iort;

> +	struct acpi_iort_node *node, *end;

> +	acpi_status status;

> +	u8 limit = 32;


Nitpick: can we not return PHYS_ADDR_MAX here, for consistency with
of_dma_get_max_cpu_address()? There wouldn't be any functional change.

-- 
Catalin