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arm64: keep J713 GPU/DCP non-coherent when CLIDR_EL1.LoC == 0 (fixes J713 graphics on 7.3) #429

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Merged
erykwieliczko merged 5 commits into from
Nov 4, 2026
Merged

arm64: keep J713 GPU/DCP non-coherent when CLIDR_EL1.LoC == 0 (fixes J713 graphics on 7.3) #429

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095c2f3
arm64: dts: apple: t6040: Drop dma-noncoherent from the display subsy…
erikwb Oct 30, 2026
2b32d51
arm64: mm: Keep explicitly dma-noncoherent devices non-coherent when …
erikwb Oct 30, 2026
4933e3e
arm64: dts: apple: t8132-j713: Mark GPU and DCP dma-noncoherent
erikwb Oct 24, 2026
ec3215d
dt-bindings: gpu: apple,agx: allow explicit non-coherent DMA
RyanTheTide Oct 25, 2026
6832149
dt-bindings: display: apple,dcp: allow explicit non-coherent DMA
erikwb Oct 26, 2026
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3 changes: 3 additions & 0 deletions Documentation/devicetree/bindings/display/apple,dcp.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,8 @@ properties:
power-domains:
maxItems: 1

dma-noncoherent: true

resets:
maxItems: 1

Expand Down Expand Up @@ -299,6 +301,7 @@ properties:
properties:
iommus:
maxItems: 1
dma-noncoherent: true
memory-region:
minItems: 1
maxItems: 64
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2 changes: 2 additions & 0 deletions Documentation/devicetree/bindings/gpu/apple,agx.yaml
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Expand Up @@ -40,6 +40,8 @@ properties:
power-domains:
maxItems: 1

dma-noncoherent: true

mboxes:
minItems: 1
maxItems: 2
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1 change: 0 additions & 1 deletion arch/arm64/boot/dts/apple/t6040.dtsi
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Expand Up @@ -522,7 +522,6 @@
display: display-subsystem {
compatible = "apple,display-subsystem";
iommus = <&disp0_dart 0>;
dma-noncoherent;
status = "disabled";
};

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5 changes: 5 additions & 0 deletions arch/arm64/boot/dts/apple/t8132-j713-display.dtsi
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Expand Up @@ -16,6 +16,8 @@
* frontend mappings it adds memory-region and apple,j713-inherited-mappings
* to piodma and display-subsystem and enables them and disp0_dart.
* apple,j713-native-piodma and apple,j713-native-scanout opt in to that.
* The DCP, PIODMA and scanout paths use non-coherent DMA only, so those
* nodes are marked dma-noncoherent.
* The DART driver also reads the ADT through the loader's phram "adt"
* region. Without that handoff the DCP and frontend are refused.
*
Expand Down Expand Up @@ -81,6 +83,7 @@
mbox-names = "mbox";
iommus = <&dcp_dart 23>;
power-domains = <&ps_disp_cpu>;
dma-noncoherent;
apple,j713-native-piodma;
apple,j713-native-scanout;
/* Full 2560x1664 panel including the notch rows, 224 ppi. */
Expand All @@ -91,13 +94,15 @@

disp0_piodma: piodma {
iommus = <&disp0_dart 16>;
dma-noncoherent;
status = "disabled"; /* Enabled by the loader. */
};
};

display: display-subsystem {
compatible = "apple,t8132-display-subsystem", "apple,t8132-display-diagnostics";
iommus = <&disp0_dart 0>;
dma-noncoherent;
status = "disabled"; /* Enabled by the loader. */
};
};
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2 changes: 2 additions & 0 deletions arch/arm64/boot/dts/apple/t8132-j713-gpu.dtsi
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Expand Up @@ -69,6 +69,8 @@
reg-names = "asc", "sgx";
mboxes = <&agx_mbox>;
power-domains = <&ps_gfx>;
/* G16 is admitted on non-coherent DMA only. */
dma-noncoherent;
apple,pmp = <&pmp>;
memory-region = <&gpu_ttbs>, <&gpu_pagetables>, <&gpu_handoff>,
<&gpu_shared_l2>, <&gpu_fw_text>, <&gpu_fw_data>;
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12 changes: 9 additions & 3 deletions arch/arm64/mm/dma-mapping.c
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Expand Up @@ -7,6 +7,7 @@
#include <linux/gfp.h>
#include <linux/cache.h>
#include <linux/dma-map-ops.h>
#include <linux/property.h>
#include <xen/xen.h>

#include <asm/cacheflush.h>
Expand Down Expand Up @@ -42,12 +43,17 @@ void arch_setup_dma_ops(struct device *dev, bool coherent)
{
int cls = cache_line_size_of_cpu();

if (!coherent && !CLIDR_LOC(read_sysreg(clidr_el1))) {
/*
* A device explicitly marked "dma-noncoherent" keeps non-coherent DMA:
* its driver may depend on the non-cacheable attributes of that path.
*/
if (!coherent && !CLIDR_LOC(read_sysreg(clidr_el1)) &&
!device_property_present(dev, "dma-noncoherent")) {
/*
* This holds for every device on the system, so say it once
* This holds for every other device on the system, so say it once
* and keep the per-device line for debugging.
*/
pr_info_once("CLIDR_EL1.LoC == 0, treating all devices as DMA coherent\n");
pr_info_once("CLIDR_EL1.LoC == 0, treating devices not marked dma-noncoherent as DMA coherent\n");
dev_dbg(dev, "CLIDR_EL1.LoC == 0, treating as coherent\n");
coherent = true;
}
Expand Down
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