Re: [PATCH 1/6] dt-bindings: ptp: Document the TSCSS on Qualcomm Lemans and Monaco SoCs

[Krzysztof Kozlowski <krzk@kernel.org>]

On 26/10/2026 13:55, Imran Shaik wrote:
>>
>>>
>>> On checking further, I found that our etu-slice sub node deviates from
>>> that example, since we don't have a compatible string for the sub node.
>>>
>>> Please let me know if we should move the pinctrl properties under the
>>> tscss node with per-slice names, or instead keep them under the
>>> etu-slice sub node and add a compatible there.
>>
>> etu-slice does not feel like device at all unfortunately. I see only
>> address space, so one resource, which might be enough but lack of
>> description for the subnode is not helping. I have doubts that separate
>> subnodes should be there in the first place, but if they stay, describe
>> the child node fully - what sort of device it is. Just because there is
>> independent timestamping counter does not make it separate device, just
>> like independent interrupt in GIC is not itself an independent device.
>>
> 
> The ETU is an independent hardware block within TSCSS that captures/

How is it independent? I see no resources, except address space. A
channel of some device does not mean it is a separate device.


> snapshots the TSC timestamp in response to an external hardware
> event trigger, for each slice individually. Hence the subnodes approach
> was followed and will capture these details in the description as well.
> 
> If we drop the subnodes and add everything into the parent TSCSS node
> instead, then all the arrays here must stay index aligned as per slice
> mapping. Example DTS node looks like this (QDU1000, 3 slices):
> 
> ptp@1da0000 {
> 	compatible = "qcom,qdu1000-tscss";
> 	reg = <0x0 0x01da0000 0x0 0x2000>,
> 	      <0x0 0x01db0000 0x0 0x10000>;
> 	reg-names = "tsc", "etu";
> 	
> 	...
> 
> 	interrupts = <GIC_SPI 329 IRQ_TYPE_EDGE_RISING>,
> 		     <GIC_SPI 333 IRQ_TYPE_EDGE_RISING>,
> 		     <GIC_SPI 334 IRQ_TYPE_EDGE_RISING>;
> 	interrupt-names = "slice1", "slice5", "slice6";
> 	
> 	pinctrl-0 = <&tod_pps>;
> 	pinctrl-1 = <&gps_pps>;
> 	pinctrl-2 = <&hardsync_pps>;
> 	pinctrl-names = "slice1", "slice5", "slice6";
> 	
> 	qcom,etu-slice = <1 5 6>;
> 	qcom,etu-event-sel = <1 3 2>;

Why this is not continuous? The slices are all fixed in the hardware. I
don't get why do you list some of them.


Best regards,
Krzysztof