On 9/20/2025 2:35 AM, Dmitry Baryshkov wrote:
> On Fri, Sep 19, 2025 at 10:24:31PM +0800, Xiangxu Yin wrote:
>> QCS615 platform requires non-default logical-to-physical lane mapping due
>> to its unique hardware routing. Unlike the standard mapping sequence
>> <0 1 2 3>, QCS615 uses <3 2 0 1>, which necessitates explicit
>> configuration via the data-lanes property in the device tree. This ensures
>> correct signal routing between the DP controller and PHY.
>>
>> For partial definitions, fill remaining lanes with unused physical lanes
>> in ascending order.
>>
>> Signed-off-by: Xiangxu Yin <xiangxu....@oss.qualcomm.com>
>> ---
>> drivers/gpu/drm/msm/dp/dp_ctrl.c | 10 +++----
>> drivers/gpu/drm/msm/dp/dp_link.c | 60
>> ++++++++++++++++++++++++++++++++++++++++
>> drivers/gpu/drm/msm/dp/dp_link.h | 1 +
>> 3 files changed, 66 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/dp/dp_link.c
>> b/drivers/gpu/drm/msm/dp/dp_link.c
>> index
>> 2aeb3ecf76fab2ee6a9512b785ca5dceebfc3964..34a91e194a124ef5372f13352f7b3513aa88da2a
>> 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_link.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_link.c
>> @@ -1236,6 +1236,61 @@ static u32 msm_dp_link_link_frequencies(struct
>> device_node *of_node)
>> return frequency;
>> }
>>
>> +/*
>> + * Always populate msm_dp_link->lane_map with 4 lanes.
>> + * - Use DTS "data-lanes" if present; otherwise fall back to default
>> mapping.
>> + * - For partial definitions, fill remaining entries with unused lanes in
>> + * ascending order.
>> + */
>> +static int msm_dp_link_lane_map(struct device *dev, struct msm_dp_link
>> *msm_dp_link)
>> +{
>> + struct device_node *of_node = dev->of_node;
>> + struct device_node *endpoint;
>> + int cnt = msm_dp_link->max_dp_lanes;
>> + u32 tmp[DP_MAX_NUM_DP_LANES];
>> + u32 map[DP_MAX_NUM_DP_LANES] = {0, 1, 2, 3}; /* default 1:1 mapping */
>> + bool used[DP_MAX_NUM_DP_LANES] = {false};
>> + int i, j = 0, ret = -EINVAL;
>> +
>> + endpoint = of_graph_get_endpoint_by_regs(of_node, 1, -1);
>> + if (endpoint) {
>> + ret = of_property_read_u32_array(endpoint, "data-lanes", tmp,
>> cnt);
>> + if (ret)
>> + dev_dbg(dev, "endpoint data-lanes read failed
>> (ret=%d)\n", ret);
>> + }
>> +
>> + if (ret) {
>> + ret = of_property_read_u32_array(of_node, "data-lanes", tmp,
>> cnt);
>> + if (ret) {
>> + dev_info(dev, "data-lanes not defined, set to
>> default\n");
>> + goto out;
>> + }
>> + }
>> +
>> + for (i = 0; i < cnt; i++) {
>> + if (tmp[i] >= DP_MAX_NUM_DP_LANES) {
>> + dev_err(dev, "data-lanes[%d]=%u out of range\n", i,
>> tmp[i]);
>> + return -EINVAL;
>> + }
>> + used[tmp[i]] = true;
>> + map[i] = tmp[i];
>> + }
>> +
>> + /* Fill the remaining entries with unused physical lanes (ascending) */
>> + for (i = cnt; i < DP_MAX_NUM_DP_LANES && j < DP_MAX_NUM_DP_LANES; j++) {
> Nit: i = cnt, j = 0; Don't init loop variables at the top of the
> function.
>
> Other than that:
>
> Reviewed-by: Dmitry Baryshkov <dmitry.barysh...@oss.qualcomm.com>
>
Ack.
>> + if (!used[j])
>> + map[i++] = j;
>> + }
>> +
>> +out:
>> + if (endpoint)
>> + of_node_put(endpoint);
>> +
>> + dev_dbg(dev, "data-lanes count %d <%d %d %d %d>\n", cnt, map[0],
>> map[1], map[2], map[3]);
>> + memcpy(msm_dp_link->lane_map, map, sizeof(map));
>> + return 0;
>> +}
>> +
>> static int msm_dp_link_parse_dt(struct device *dev, struct msm_dp_link
>> *msm_dp_link)
>> {
>> struct device_node *of_node = dev->of_node;
