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: <141e33fc-c963-4f58-a69c-e7068c9ec6e8@oss.qualcomm.com>
Date: Wed, 8 Oct 2025 11:31:36 +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,
        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 10/6/25 3:55 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));

if (*count > max)
	return -EINVAL;

> +
> +err_node_put:
> +	of_node_put(ep);

__free(device_node)

> +
> +	return ret;
> +}
> +
> +static int qmp_combo_get_dt_dp_orientation(struct device *dev,
> +					     enum typec_orientation *orientation)
> +{
> +	unsigned int count;
> +	u32 data_lanes[4];
> +	int ret;
> +
> +	/* DP is described on the first endpoint of the first port */
> +	ret = qmp_combo_get_dt_lanes_mapping(dev, 0, data_lanes, 4, &count);
> +	if (ret < 0)
> +		return ret == -EINVAL ? 0 : ret;
> +
> +	/* Search for a match and only update orientation if found */
> +	qmp_combo_find_lanes_orientation(dp_data_lanes, ARRAY_SIZE(dp_data_lanes),
> +					 data_lanes, count, orientation);

You can zero-initialize `count` and drop the custom error parsing above

Konrad