linux-kernel - Re: [PATCH v4 2/3] phy: qcom: qmp-combo: get the USB3 & DisplayPort lanes mapping from DT

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Message-ID: <8e871a21-5f1b-44c7-ae53-733c91e34471@oss.qualcomm.com>
Date: Mon, 6 Oct 2025 16:54:47 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Neil Armstrong <neil.armstrong@...aro.org>, Vinod Koul
 <vkoul@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>
Cc: Xilin Wu <sophon@...xa.com>, linux-arm-msm@...r.kernel.org,
        linux-phy@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/3] phy: qcom: qmp-combo: get the USB3 & DisplayPort
 lanes mapping from DT

On 10/6/25 2:50 PM, Neil Armstrong wrote:
> On 10/6/25 12:08, Konrad Dybcio wrote:
>> On 9/30/25 9:39 AM, Neil Armstrong wrote:
>>> The QMP USB3/DP Combo PHY hosts an USB3 phy and a DP PHY on top
>>> of a combo glue to route either lanes to the 4 shared physical lanes.
>>>
>>> The routing of the lanes can be:
>>> - 2 DP + 2 USB3
>>> - 4 DP
>>> - 2 USB3
>>>
>>> Get the lanes mapping from DT and stop registering the USB-C
>>> muxes in favor of a static mode and orientation detemined
>>> by the lanes mapping.
>>>
>>> This allows supporting boards with direct connection of USB3 and
>>> DisplayPort lanes to the QMP Combo PHY lanes, not using the
>>> USB-C Altmode feature.
>>>
>>> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
>>> ---

[...]
>>> +    { 2, TYPEC_ORIENTATION_NORMAL, { 3, 2 }},
>>> +    { 2, TYPEC_ORIENTATION_REVERSE, { 0, 1 }},
>>> +    { 4, TYPEC_ORIENTATION_NORMAL, { 3, 2, 1, 0 }},
>>> +    { 4, TYPEC_ORIENTATION_REVERSE, { 0, 1, 2, 3 }},
>>
>> Would it be too cheesy to check orientation based like:
>>
>> static bool qmpphy_mapping_orient_flipped(u32 *data_lanes)
>> {
>>     return data_lanes[0] == 0;
>> }
>>
>> ?
> 
> Do we want a proper check of the property content or some random check ?
> Sorry I prefer something formal, since perhaps sometime we will have
> a full lanes remapping available instead of just orientation and if
> we have some random input it will explose...

Well you already list all accepted properties. This would only (slightly)
limit the amount of storage the data that you *then associate with it*
occupies, but I'm not going to die on this hill, do as you prefer..

Konrad