linux-kernel - Re: [PATCH v2 1/2] dt-bindings: usb: Introduce ITE IT5205 Alt. Mode Passive MUX

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Message-ID: <9605c20a-12ad-49ad-8114-d59f2f772514@collabora.com>
Date: Mon, 22 Jan 2024 11:27:11 +0100
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Conor Dooley <conor@...nel.org>
Cc: gregkh@...uxfoundation.org, robh+dt@...nel.org,
 krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
 heikki.krogerus@...ux.intel.com, matthias.bgg@...il.com,
 dmitry.baryshkov@...aro.org, neil.armstrong@...aro.org,
 andersson@...nel.org, nathan@...nel.org, luca.weiss@...rphone.com,
 tianping.fang@...iatek.com, linux-usb@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org,
 kernel@...labora.com
Subject: Re: [PATCH v2 1/2] dt-bindings: usb: Introduce ITE IT5205 Alt. Mode
 Passive MUX

Il 19/01/24 17:18, Conor Dooley ha scritto:
> On Fri, Jan 19, 2024 at 01:58:11PM +0100, AngeloGioacchino Del Regno wrote:
>> Introduce a binding for the ITE IT5205 Alternate Mode Passive MUX,
>> used for connecting, disconnecting and switching orientation and
>> control the SBU signals for alternate modes on USB Type-C ports.
>>
>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
>> ---
>>   .../devicetree/bindings/usb/ite,it5205.yaml   | 72 +++++++++++++++++++
>>   1 file changed, 72 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/usb/ite,it5205.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/usb/ite,it5205.yaml b/Documentation/devicetree/bindings/usb/ite,it5205.yaml
>> new file mode 100644
>> index 000000000000..36ec4251b5f2
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/usb/ite,it5205.yaml
>> @@ -0,0 +1,72 @@
>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/usb/ite,it5205.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: ITE IT5202 Type-C USB Alternate Mode Passive MUX
>> +
>> +maintainers:
>> +  - AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
>> +  - Tianping Fang <tianping.fang@...iatek.com>
>> +
>> +properties:
>> +  compatible:
>> +    const: ite,it5205
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  vcc-supply:
>> +    description: Power supply for VCC pin (3.3V)
>> +
>> +  mode-switch:
>> +    description: Flag the port as possible handle of altmode switching
>> +    type: boolean
>> +
>> +  orientation-switch:
>> +    description: Flag the port as possible handler of orientation switching
>> +    type: boolean
>> +
>> +  ite,ovp-enable:
>> +    description: Enable Over Voltage Protection functionality
>> +    type: boolean
> 
> Bitta devil's advocacy perhaps, but why is this DT property? Is it not
> known whether or not this is supported based on the compatible, and
> whether or not to enable it is a decision for the operating system to
> make?
> 
> 

AFAIK, not all board designs can use the OVP. On some, this may be unstable - the
use case where this can be safely enabled is when there's nothing in between the
mux and the controller, and between the mux and the port.

Cheers,
Angelo