[PATCH v2 0/2] Fix traceNoC probe issue on Kaanapali

[PATCH v2 0/2] Fix traceNoC probe issue on Kaanapali

[Jie Gan]

Patch 1 changes the binding to allow the TraceNoC device accepts
arm,primecell-periphid property.

Patch 2 fixes the deferred probe issue for the TraceNoC device by
adding the arm,primecell-periphid property to bypass the AMBA check.

Signed-off-by: Jie Gan <jie.gan@oss.qualcomm.com>
---
Changes in v2:
- address the ATID issue reported by Sashiko.
- update binding to accept arm,primecell-periphid property.
- Link to v1: https://lore.kernel.org/r/20260624-fix-tracenoc-probe-issue-v1-1-bcc785198fc5@oss.qualcomm.com

---
Jie Gan (2):
      dt-bindings: arm: qcom,coresight-tnoc: allow arm,primecell-periphid
      arm64: dts: qcom: kaanapali: fix traceNoC probe issue

 Documentation/devicetree/bindings/arm/qcom,coresight-tnoc.yaml | 5 ++++-
 arch/arm64/boot/dts/qcom/kaanapali.dtsi                        | 1 +
 2 files changed, 5 insertions(+), 1 deletion(-)
---
base-commit: 4e5dfb7c84012007c3c7061126491bbc92d71bf1
change-id: 20260624-fix-tracenoc-probe-issue-c6429da28df4

Best regards,
-- 
Jie Gan <jie.gan@oss.qualcomm.com>

[PATCH v2 1/2] dt-bindings: arm: qcom,coresight-tnoc: allow arm,primecell-periphid

[Jie Gan]

The TNOC device is an AMBA primecell and may carry the standard
arm,primecell-periphid property, which is used to supply the
peripheral ID when it cannot be read from the device registers.

Reference primecell.yaml and set additionalProperties to true so the
binding accepts arm,primecell-periphid along with the other common
primecell properties.

Signed-off-by: Jie Gan <jie.gan@oss.qualcomm.com>
---
 Documentation/devicetree/bindings/arm/qcom,coresight-tnoc.yaml | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/arm/qcom,coresight-tnoc.yaml b/Documentation/devicetree/bindings/arm/qcom,coresight-tnoc.yaml
index ef648a15b806..9624fc0adfdc 100644
--- a/Documentation/devicetree/bindings/arm/qcom,coresight-tnoc.yaml
+++ b/Documentation/devicetree/bindings/arm/qcom,coresight-tnoc.yaml
@@ -32,6 +32,9 @@ select:
   required:
     - compatible
 
+allOf:
+  - $ref: /schemas/arm/primecell.yaml#
+
 properties:
   $nodename:
     pattern: "^tn(@[0-9a-f]+)$"
@@ -78,7 +81,7 @@ required:
   - in-ports
   - out-ports
 
-additionalProperties: false
+additionalProperties: true
 
 examples:
   - |

-- 
2.34.1

[PATCH v2 2/2] arm64: dts: qcom: kaanapali: fix traceNoC probe issue

[Jie Gan]

The AMBA bus attempts to read the CID/PID of a device before invoking
its probe function if the arm,primecell-periphid property is absent.
This causes a deferred probe issue for the TraceNoC device, as the
CID/PID cannot be read from the periphid register.
Add the arm,primecell-periphid property to bypass the AMBA bus
check and resolve the probe issue.

Fixes: f73959d86c15 ("arm64: dts: qcom: kaanapali: add coresight nodes")
Signed-off-by: Jie Gan <jie.gan@oss.qualcomm.com>
---
 arch/arm64/boot/dts/qcom/kaanapali.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/qcom/kaanapali.dtsi b/arch/arm64/boot/dts/qcom/kaanapali.dtsi
index 7aa9653bd456..25820f7c04cd 100644
--- a/arch/arm64/boot/dts/qcom/kaanapali.dtsi
+++ b/arch/arm64/boot/dts/qcom/kaanapali.dtsi
@@ -5009,6 +5009,7 @@ tn@111b8000 {
 
 			clocks = <&aoss_qmp>;
 			clock-names = "apb_pclk";
+			arm,primecell-periphid = <0x000f0c00>;
 
 			in-ports {
 				#address-cells = <1>;

-- 
2.34.1

Re: [PATCH v2 1/2] dt-bindings: arm: qcom,coresight-tnoc: allow arm,primecell-periphid

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Setting `additionalProperties: true` completely disables strict schema validation for undefined properties, allowing misspelled or undocumented properties to silently pass.
--

commit 6e8606766f1fd41047be4a5d6a3178b5f3fd67e9
Author: Jie Gan <jie.gan@oss.qualcomm.com>

dt-bindings: arm: qcom,coresight-tnoc: allow arm,primecell-periphid

This commit updates the qcom,coresight-tnoc binding to reference
primecell.yaml. It changes additionalProperties to true to allow
the arm,primecell-periphid property along with other common properties.

> diff --git a/Documentation/devicetree/bindings/arm/qcom,coresight-tnoc.yaml b/Documentation/devicetree/bindings/arm/qcom,coresight-tnoc.yaml
> --- a/Documentation/devicetree/bindings/arm/qcom,coresight-tnoc.yaml
> +++ b/Documentation/devicetree/bindings/arm/qcom,coresight-tnoc.yaml
[ ... ]
> @@ -78,7 +81,7 @@ required:
>    - in-ports
>    - out-ports
>  
> -additionalProperties: false
> +additionalProperties: true

[Severity: Medium]
Does setting additionalProperties to true completely disable strict schema
validation for this node? 

It looks like this change will cause misspelled properties to silently pass
during make dt_binding_check. When adding a $ref in an allOf block, should
unevaluatedProperties: false be used instead? That would allow the inherited
primecell.yaml properties to pass while still rejecting any undefined or
typoed properties.

>  
>  examples:
>    - |

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260624-fix-tracenoc-probe-issue-v2-0-786520f62f21@oss.qualcomm.com?part=1

Re: [PATCH v2 2/2] arm64: dts: qcom: kaanapali: fix traceNoC probe issue

[Konrad Dybcio]

On 6/24/26 11:49 AM, Jie Gan wrote:
> The AMBA bus attempts to read the CID/PID of a device before invoking
> its probe function if the arm,primecell-periphid property is absent.
> This causes a deferred probe issue for the TraceNoC device, as the
> CID/PID cannot be read from the periphid register.

Why does it probe defer?

And is this required for all TNOC devices?

Konrad

Re: [PATCH v2 2/2] arm64: dts: qcom: kaanapali: fix traceNoC probe issue

[Jie Gan]

On 6/24/2026 9:27 PM, Konrad Dybcio wrote:
> On 6/24/26 11:49 AM, Jie Gan wrote:
>> The AMBA bus attempts to read the CID/PID of a device before invoking
>> its probe function if the arm,primecell-periphid property is absent.
>> This causes a deferred probe issue for the TraceNoC device, as the
>> CID/PID cannot be read from the periphid register.
> 
> Why does it probe defer?
> 

For an AMBA device, the periphid is mandatory for probing. In the 
amba_match function, AMBA attempts to read the periphid from the CID/PID 
registers if the arm,primecell-periphid property is absent in the device 
tree. If this read fails, it returns -EPROBE_DEFER, and the probe 
ultimately fails.
Most AMBA devices expose valid CID/PID registers, so specifying 
arm,primecell-periphid in the device tree is usually unnecessary. 
However, for the TraceNoC device in this case, AMBA cannot reliably read 
the periphid from the corresponding registers.

> And is this required for all TNOC devices?

So far, the TNOC device has been added to sm8750, Glymur, and Kaanapali 
platforms, and all exhibit probe failures due to the same root cause.

I prefer to fix it on Kaanapali first.

Thanks,
Jie

> 
> Konrad

Re: [PATCH v2 2/2] arm64: dts: qcom: kaanapali: fix traceNoC probe issue

[Suzuki K Poulose]

On 24/06/2026 14:48, Jie Gan wrote:
> 
> 
> On 6/24/2026 9:27 PM, Konrad Dybcio wrote:
>> On 6/24/26 11:49 AM, Jie Gan wrote:
>>> The AMBA bus attempts to read the CID/PID of a device before invoking
>>> its probe function if the arm,primecell-periphid property is absent.
>>> This causes a deferred probe issue for the TraceNoC device, as the
>>> CID/PID cannot be read from the periphid register.
>>
>> Why does it probe defer?
>>
> 
> For an AMBA device, the periphid is mandatory for probing. In the 
> amba_match function, AMBA attempts to read the periphid from the CID/PID 
> registers if the arm,primecell-periphid property is absent in the device 
> tree. If this read fails, it returns -EPROBE_DEFER, and the probe 
> ultimately fails.

Why does it fail ? power management ? hw broken ? Is it really AMBA or 
do you pretend that to be an AMBA device by faking the CID/PID?

Suzuki


> Most AMBA devices expose valid CID/PID registers, so specifying 
> arm,primecell-periphid in the device tree is usually unnecessary. 
> However, for the TraceNoC device in this case, AMBA cannot reliably read 
> the periphid from the corresponding registers.
> 
>> And is this required for all TNOC devices?
> 
> So far, the TNOC device has been added to sm8750, Glymur, and Kaanapali 
> platforms, and all exhibit probe failures due to the same root cause.
> 
> I prefer to fix it on Kaanapali first.
> 
> Thanks,
> Jie
> 
>>
>> Konrad
> 

Re: [PATCH v2 2/2] arm64: dts: qcom: kaanapali: fix traceNoC probe issue

[Leo Yan]

On Wed, Jun 24, 2026 at 05:49:26PM +0800, Jie Gan wrote:
> The AMBA bus attempts to read the CID/PID of a device before invoking
> its probe function if the arm,primecell-periphid property is absent.
> This causes a deferred probe issue for the TraceNoC device, as the
> CID/PID cannot be read from the periphid register.
> Add the arm,primecell-periphid property to bypass the AMBA bus
> check and resolve the probe issue.

tnoc.c registers both an AMBA driver and a platform driver. Shouldn't it
be registered as a platform device instead?

Thanks,
Leo

Re: [PATCH v2 2/2] arm64: dts: qcom: kaanapali: fix traceNoC probe issue

[Jie Gan]

On 6/24/2026 9:51 PM, Suzuki K Poulose wrote:
> On 24/06/2026 14:48, Jie Gan wrote:
>>
>>
>> On 6/24/2026 9:27 PM, Konrad Dybcio wrote:
>>> On 6/24/26 11:49 AM, Jie Gan wrote:
>>>> The AMBA bus attempts to read the CID/PID of a device before invoking
>>>> its probe function if the arm,primecell-periphid property is absent.
>>>> This causes a deferred probe issue for the TraceNoC device, as the
>>>> CID/PID cannot be read from the periphid register.
>>>
>>> Why does it probe defer?
>>>
>>
>> For an AMBA device, the periphid is mandatory for probing. In the 
>> amba_match function, AMBA attempts to read the periphid from the CID/ 
>> PID registers if the arm,primecell-periphid property is absent in the 
>> device tree. If this read fails, it returns -EPROBE_DEFER, and the 
>> probe ultimately fails.
> 
> Why does it fail ? power management ? hw broken ? Is it really AMBA or 
> do you pretend that to be an AMBA device by faking the CID/PID?

The CID reads as 0 from the register, which I suspect is a hardware 
design issue. I have not yet confirmed this with the hardware team. As a 
workaround, I provided a fake periphid via a DT property to bypass 
amba_read_periphid.


Leo commented in other thread:
 >>tnoc.c registers both an AMBA driver and a platform driver. Shouldn't 
 >>it
 >>be registered as a platform device instead?

The platform driver is intended for the interconnect TraceNoC device and 
is not designed to allocate an ATID. The issue is that the TPDM device 
borrows the ATID from the TraceNoC device, resulting in the ATID always 
being 0 when associated with an interconnect NoC device.

However, I believe it is acceptable to allocate an ATID for the itNoC 
device and the issue can be fixed with this way.

Thanks,
Jie

> 
> Suzuki
> 
> 
>> Most AMBA devices expose valid CID/PID registers, so specifying 
>> arm,primecell-periphid in the device tree is usually unnecessary. 
>> However, for the TraceNoC device in this case, AMBA cannot reliably 
>> read the periphid from the corresponding registers.
>>
>>> And is this required for all TNOC devices?
>>
>> So far, the TNOC device has been added to sm8750, Glymur, and 
>> Kaanapali platforms, and all exhibit probe failures due to the same 
>> root cause.
>>
>> I prefer to fix it on Kaanapali first.
>>
>> Thanks,
>> Jie
>>
>>>
>>> Konrad
>>
> 

Re: [PATCH v2 2/2] arm64: dts: qcom: kaanapali: fix traceNoC probe issue

[Leo Yan]

On Wed, Jun 24, 2026 at 11:08:32PM +0800, Jie Gan wrote:

[...]

> > Why does it fail ? power management ? hw broken ? Is it really AMBA or
> > do you pretend that to be an AMBA device by faking the CID/PID?
> 
> The CID reads as 0 from the register, which I suspect is a hardware design
> issue. I have not yet confirmed this with the hardware team. As a
> workaround, I provided a fake periphid via a DT property to bypass
> amba_read_periphid.
> 
> 
> Leo commented in other thread:
> >>tnoc.c registers both an AMBA driver and a platform driver. Shouldn't >>it
> >>be registered as a platform device instead?
> 
> The platform driver is intended for the interconnect TraceNoC device and is
> not designed to allocate an ATID. The issue is that the TPDM device borrows
> the ATID from the TraceNoC device, resulting in the ATID always being 0 when
> associated with an interconnect NoC device.
> 
> However, I believe it is acceptable to allocate an ATID for the itNoC device
> and the issue can be fixed with this way.

I think so.