[v2] ARM: dts: integrator: Fix DMA ranges

Commit Message

Linus Walleij Sept. 26, 2022, 7:33 a.m. UTC

A recent change affecting the behaviour of phys_to_dma() to
actually require the device tree ranges to work unmasked a
bug in the Integrator DMA ranges.

The PL110 uses the CMA allocator to obtain coherent allocations
from a dedicated 1MB video memory, leading to the following
call chain:

drm_gem_cma_create()
  dma_alloc_attrs()
    dma_alloc_from_dev_coherent()
      __dma_alloc_from_coherent()
        dma_get_device_base()
          phys_to_dma()
            translate_phys_to_dma()

phys_to_dma() by way of translate_phys_to_dma() will nowadays not
provide 1:1 mappings unless the ranges are properly defined in
the device tree and reflected into the dev->dma_range_map.

There is a bug in the device trees because the DMA ranges are
incorrectly specified, and the patch uncovers this bug.

Solution:

- Fix the LB (logic bus) ranges to be 1-to-1 like they should
  have always been.
- Provide a 1:1 dma-ranges attribute to the PL110.
- Mark the PL110 display controller as DMA coherent.

This makes the DMA ranges work right and makes the PL110
framebuffer work again.

Cc: Christoph Hellwig <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: [e-mail]
Fixes: af6f23b88e95 ("ARM/dma-mapping: use the generic versions of dma_to_phys/phys_to_dma by default")
Signed-off-by: Linus Walleij <[e-mail]>
---
ChangeLog v1->v2:
- Drom dma-coherent, this device is not cache coherent
  whatsoever, just my misunderstanding.
- Change Fixes: tag to a hopefully more appropriate one.
- Update commit message.

SoC folks: please apply this directly for fixes if it seems
to be the right thing to do.
---
 arch/arm/boot/dts/integratorap-im-pd1.dts | 1 +
 arch/arm/boot/dts/integratorap.dts        | 8 ++++----
 2 files changed, 5 insertions(+), 4 deletions(-)

Comments

[e-mail] Sept. 26, 2022, 9:30 p.m. UTC | #1

Hello:

This patch was applied to soc/soc.git (arm/fixes)
by Arnd Bergmann <[e-mail]>:

On Mon, 26 Sep 2022 09:33:11 +0200 you wrote:
> A recent change affecting the behaviour of phys_to_dma() to
> actually require the device tree ranges to work unmasked a
> bug in the Integrator DMA ranges.
> 
> The PL110 uses the CMA allocator to obtain coherent allocations
> from a dedicated 1MB video memory, leading to the following
> call chain:
> 
> [...]

Here is the summary with links:
  - [v2] ARM: dts: integrator: Fix DMA ranges
    https://git.kernel.org/soc/soc/c/7bea67a99430

You are awesome, thank you!

Patch

diff --git a/arch/arm/boot/dts/integratorap-im-pd1.dts b/arch/arm/boot/dts/integratorap-im-pd1.dts
index 31724753d3f3..14fab499f0fa 100644
--- a/arch/arm/boot/dts/integratorap-im-pd1.dts
+++ b/arch/arm/boot/dts/integratorap-im-pd1.dts
@@ -248,6 +248,7 @@  display@1000000 {
 		/* 640x480 16bpp @ 25.175MHz is 36827428 bytes/s */
 		max-memory-bandwidth = <40000000>;
 		memory-region = <&impd1_ram>;
+		dma-ranges;
 
 		port@0 {
 			#address-cells = <1>;
diff --git a/arch/arm/boot/dts/integratorap.dts b/arch/arm/boot/dts/integratorap.dts
index c983435ed492..9148287fa0a9 100644
--- a/arch/arm/boot/dts/integratorap.dts
+++ b/arch/arm/boot/dts/integratorap.dts
@@ -262,7 +262,7 @@  bus@c0000000 {
 		lm0: bus@c0000000 {
 			compatible = "simple-bus";
 			ranges = <0x00000000 0xc0000000 0x10000000>;
-			dma-ranges = <0x00000000 0x80000000 0x10000000>;
+			dma-ranges = <0x00000000 0xc0000000 0x10000000>;
 			reg = <0xc0000000 0x10000000>;
 			#address-cells = <1>;
 			#size-cells = <1>;
@@ -270,7 +270,7 @@  lm0: bus@c0000000 {
 		lm1: bus@d0000000 {
 			compatible = "simple-bus";
 			ranges = <0x00000000 0xd0000000 0x10000000>;
-			dma-ranges = <0x00000000 0x80000000 0x10000000>;
+			dma-ranges = <0x00000000 0xd0000000 0x10000000>;
 			reg = <0xd0000000 0x10000000>;
 			#address-cells = <1>;
 			#size-cells = <1>;
@@ -278,7 +278,7 @@  lm1: bus@d0000000 {
 		lm2: bus@e0000000 {
 			compatible = "simple-bus";
 			ranges = <0x00000000 0xe0000000 0x10000000>;
-			dma-ranges = <0x00000000 0x80000000 0x10000000>;
+			dma-ranges = <0x00000000 0xe0000000 0x10000000>;
 			reg = <0xe0000000 0x10000000>;
 			#address-cells = <1>;
 			#size-cells = <1>;
@@ -286,7 +286,7 @@  lm2: bus@e0000000 {
 		lm3: bus@f0000000 {
 			compatible = "simple-bus";
 			ranges = <0x00000000 0xf0000000 0x10000000>;
-			dma-ranges = <0x00000000 0x80000000 0x10000000>;
+			dma-ranges = <0x00000000 0xf0000000 0x10000000>;
 			reg = <0xf0000000 0x10000000>;
 			#address-cells = <1>;
 			#size-cells = <1>;