linux-kernel - Re: [PATCH 1/2] dt-bindings: counter: Add new ti,omap-dmtimer-cap compatible

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Message-ID: <1561d6f5-bc60-4b41-aef5-3e22a23ee133@kernel.org>
Date: Tue, 7 Oct 2025 18:39:07 +0900
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Gokul Praveen <g-praveen@...com>, j-keerthy@...com, vigneshr@...com,
 wbg@...nel.org, linux-kernel@...r.kernel.org, robh@...nel.org,
 krzk+dt@...nel.org, conor+dt@...nel.org, devicetree@...r.kernel.org
Cc: u-kumar1@...com, n-francis@...com
Subject: Re: [PATCH 1/2] dt-bindings: counter: Add new ti,omap-dmtimer-cap
 compatible

On 07/10/2025 18:23, Gokul Praveen wrote:
> Hi Krzysztof,
> 
> 
> On 07/10/25 12:05, Krzysztof Kozlowski wrote:
>> On 26/09/2025 18:06, Gokul Praveen wrote:
>>>>
>>>>> +
>>>>> +  ti,timers:
>>>>> +    description: Timer instance phandle for the Capture
>>>>
>>>> So the only resource is phandle? That's completely fake device then. NAK.
>>>>
>>>
>>>
>>> The OMAP Timer IP can operate in 3 modes: Timer, PWM mode or capture
>>> (mutually exclusive).
>>> The timer/ti,timer-dm.yaml file describes the timer mode of operation.
>>> It encapsulates base IP block and reg property is also part the same
>>> binding.
>>>
>>> This node represents the capture mode with phandle reference to the
>>> timer DT node. This is modeled all the same lines as how PWM
>>> functionality is implemented in pwm/ti,omap-dmtimer-pwm.yaml
>>
>> Different modes do not have their own device nodes. It is still one
>> device, so one device node.
>>
>>>
>>> Now, if this needs to change, please suggest alternate.
>>>
>>> One solution is perhaps to add a new property to ti,timer-dm.yaml itself
>>> to indicate the mode of IP?
>>
>> Not sure, depends what this really is and how it is used. I can also
>> imagine that consumer defines the mod of operation.
>>
> 
> For a timer operating in capture mode, there are no consumers actually 
> and the only way we use it is through sysfs.
> 
> Would it be good enough if I have a separate "mode" property for the 
> dmtimer device node just like how it is done for USB as follows where 
> the usb device node has a "dr_mode" property to decide on whether the 
> usb should act in host, device or otg mode.


No, because of all my other comments in previous email.


Best regards,
Krzysztof