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Message-ID: <2a6393d4-47e6-1526-d68b-f34394b1dca4@ti.com>
Date:   Fri, 14 Apr 2023 20:13:58 +0530
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Subject: Re: [PATCH v2 1/2] dt-bindings: drm/bridge: Add no-hpd property
To:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>
CC:     <dri-devel@lists.freedesktop.org>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <krzysztof.kozlowski@linaro.org>,
        <andrzej.hajda@intel.com>, <neil.armstrong@linaro.org>,
        <rfoss@kernel.org>, <jonas@kwiboo.se>, <jernej.skrabec@gmail.com>,
        <airlied@gmail.com>, <daniel@ffwll.ch>, <robh+dt@kernel.org>,
        <krzysztof.kozlowski+dt@linaro.org>, <sam@ravnborg.org>,
        <jani.nikula@intel.com>, <tzimmermann@suse.de>,
        <javierm@redhat.com>, <ville.syrjala@linux.intel.com>,
        <r-ravikumar@ti.com>, <lyude@redhat.com>,
        <alexander.deucher@amd.com>, <sjakhade@cadence.com>,
        <yamonkar@cadence.com>, <a-bhatia1@ti.com>,
        <tomi.valkeinen@ideasonboard.com>
References: <20230405142440.191939-1-j-choudhary@ti.com>
 <20230405142440.191939-2-j-choudhary@ti.com>
 <20230406014032.GN9915@pendragon.ideasonboard.com>
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From:   Jayesh Choudhary <j-choudhary@ti.com>
In-Reply-To: <20230406014032.GN9915@pendragon.ideasonboard.com>
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On 06/04/23 07:10, Laurent Pinchart wrote:
> Hi Jayesh,
> 
> Thank you for the patch.
> 
> On Wed, Apr 05, 2023 at 07:54:39PM +0530, Jayesh Choudhary wrote:
>> From: Rahul T R <r-ravikumar@ti.com>
>>
>> The mhdp bridge can work without its HPD pin hooked up to the connector,
>> but the current bridge driver throws an error when hpd line is not
>> connected to the connector. For such cases, we need an indication for
>> no-hpd, using which we can bypass the hpd detection and instead use the
>> auxiliary channels connected to the DP connector to confirm the
>> connection.
>> So add no-hpd property to the bindings, to disable hpd when not
>> connected or unusable.
>>
>> Signed-off-by: Rahul T R <r-ravikumar@ti.com>
>> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
>> ---
>>   .../devicetree/bindings/display/bridge/cdns,mhdp8546.yaml   | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8546.yaml b/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8546.yaml
>> index c2b369456e4e..3a6c6d837593 100644
>> --- a/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8546.yaml
>> +++ b/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8546.yaml
>> @@ -57,6 +57,12 @@ properties:
>>     interrupts:
>>       maxItems: 1
>>   
>> +  cdns,no-hpd:
>> +    type: boolean
>> +    description:
>> +      Set if the HPD line on the bridge isn't hooked up to anything or is
>> +      otherwise unusable.
> 
> I'm fine with the non connected part, but concerned with "otherwise
> unusable". It's very vague and could thus be abused. Do you have
> particular use cases in mind for this ? If so, restricting this to those
> use cases, or at least giving examples, would help.

Okay. Will do that in next version.

Thanks.

> 
>> +
>>     ports:
>>       $ref: /schemas/graph.yaml#/properties/ports
>>   
>