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: <4bb1c10d-b8fe-485e-b4aa-faa43033be76@linaro.org>
Date: Mon, 6 Oct 2025 14:50:13 +0200
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
 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 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>
>> ---
> 
> [...]
> 
>> +struct qmp_combo_lane_mapping {
>> +	unsigned int lanes_count;
> 
> "num_lanes"?

Is this significant ?

> 
>> +	enum typec_orientation orientation;
>> +	u32 lanes[4];
>> +};
>> +
>> +static const struct qmp_combo_lane_mapping usb3_data_lanes[] = {
>> +	{ 2, TYPEC_ORIENTATION_NORMAL, { 1, 0 }},
>> +	{ 2, TYPEC_ORIENTATION_REVERSE, { 2, 3 }},
>> +};
>> +
>> +static const struct qmp_combo_lane_mapping dp_data_lanes[] = {
>> +	{ 1, TYPEC_ORIENTATION_NORMAL, { 0 }},
>> +	{ 1, TYPEC_ORIENTATION_REVERSE, { 3 }},
> 
> This is not corroborated by your bindings change ^

Damn you're right, I'll fix it...

> 
> I'm also frankly not sure whether it's pin 2 or 3 that 1-lane-DP
> would be TXd on
> 
>> +	{ 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...

> 
>> -	ret = qmp_combo_typec_register(qmp);
>> -	if (ret)
>> -		goto err_node_put;
>> +	qmp->qmpphy_mode = QMPPHY_MODE_USB3DP;
>> +
>> +	if (of_find_property(dev->of_node, "mode-switch", NULL) ||
>> +	    of_find_property(dev->of_node, "orientation-switch", NULL)) {
> 
> of_property_present()

I'll replace with that.

Thanks,
Neil

> 
> Konrad