[PATCH v4 0/7] arm64: Default to 32-bit wide ZONE_DMA

[PATCH v4 0/7] 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 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(-)

-- 
2.28.0

[PATCH v4 7/7] mm: Remove examples from enum zone_type comment

[Nicolas Saenz Julienne]

We can't really list every setup in common code. On top of that they are
unlikely to stay true for long as things change in the arch trees
independently of this comment.

Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 include/linux/mmzone.h | 20 --------------------
 1 file changed, 20 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index fb3bf696c05e..9d0c454d23cd 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -354,26 +354,6 @@ enum zone_type {
 	 * DMA mask is assumed when ZONE_DMA32 is defined. Some 64-bit
 	 * platforms may need both zones as they support peripherals with
 	 * different DMA addressing limitations.
-	 *
-	 * Some examples:
-	 *
-	 *  - i386 and x86_64 have a fixed 16M ZONE_DMA and ZONE_DMA32 for the
-	 *    rest of the lower 4G.
-	 *
-	 *  - 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.
-	 *
-	 *  - powerpc only uses ZONE_DMA, the size, up to 2G, may vary
-	 *    depending on the specific device.
-	 *
-	 *  - s390 uses ZONE_DMA fixed to the lower 2G.
-	 *
-	 *  - ia64 and riscv only use ZONE_DMA32.
-	 *
-	 *  - parisc uses neither.
 	 */
 #ifdef CONFIG_ZONE_DMA
 	ZONE_DMA,
-- 
2.28.0

Re: [PATCH v4 7/7] mm: Remove examples from enum zone_type comment

[Christoph Hellwig]

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH v4 0/7] arm64: Default to 32-bit wide ZONE_DMA

[Jeremy Linton]

Hi,

On 10/21/20 7:34 AM, Nicolas Saenz Julienne wrote:
> 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.

I've tested this in ACPI mode on the rpi4 (4+8G with/without the 3G 
limiter) as well, with Ard's IORT patch. Nothing seems to have regressed.

Thanks,

Tested-by: Jeremy Linton <jeremy.linton@arm.com>




> 
> ---
> 
> 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(-)
> 

Re: [PATCH v4 0/7] arm64: Default to 32-bit wide ZONE_DMA

[Nicolas Saenz Julienne]

[-- Attachment #1: Type: text/plain, Size: 524 bytes --]

On Fri, 2020-10-23 at 14:05 -0500, Jeremy Linton wrote:
> Hi,
> 
> On 10/21/20 7:34 AM, Nicolas Saenz Julienne wrote:
> > 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.
> 
> I've tested this in ACPI mode on the rpi4 (4+8G with/without the 3G 
> limiter) as well, with Ard's IORT patch. Nothing seems to have regressed.
> 
> Thanks,
> 
> Tested-by: Jeremy Linton <jeremy.linton@arm.com>

Thanks!


[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 488 bytes --]