linux-kernel - Re: [PATCH v5 2/3] phy: qcom: qmp-combo: get the USB3 & DisplayPort lanes mapping from DT

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Message-ID: <6941e754-0c2b-42b5-a01b-54351e8714f1@linaro.org>
Date: Thu, 9 Oct 2025 18:38:12 +0200
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Xilin Wu <sophon@...xa.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: linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Subject: Re: [PATCH v5 2/3] phy: qcom: qmp-combo: get the USB3 & DisplayPort
 lanes mapping from DT

On 10/9/25 16:51, Xilin Wu wrote:
> On 10/6/2025 9:55 PM, 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.
>>
>> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
>> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
>> ---
> 
> [...]
>> +static int qmp_combo_get_dt_lanes_mapping(struct device *dev, unsigned int endpoint,
>> +                      u32 *data_lanes, unsigned int max,
>> +                      unsigned int *count)
>> +{
>> +    struct device_node *ep;
>> +    int ret;
>> +
>> +    ep = of_graph_get_endpoint_by_regs(dev->of_node, 0, endpoint);
>> +    if (!ep)
>> +        return -EINVAL;
>> +
>> +    ret = of_property_count_u32_elems(ep, "data-lanes");
>> +    if (ret < 0)
>> +        goto err_node_put;
>> +
>> +    *count = ret;
>> +
>> +    ret = of_property_read_u32_array(ep, "data-lanes", data_lanes,
>> +                     max_t(unsigned int, *count, max));
> 
> I think this should be min_t instead of max_t.

You're right, thanks for noticing !

> 
> With this fixed,
> 
> Tested-by: Xilin Wu <sophon@...xa.com> # qcs6490-radxa-dragon-q6a
> 


Thanks,
Neil