On Mon, Sep 22, 2025 at 08:13:00AM -0700, Rob Clark wrote: > On Fri, Sep 19, 2025 at 11:35 AM Dmitry Baryshkov > <[email protected]> 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 <[email protected]> > > > --- > > > 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. > > These days we can party like it's c99 and declare loop variables > inside the for(), instead of at the top of the function. My > preference is to do so, unless the loop variable is used after the > loop.
Ack, works for me too. I think I'm not used for having theese parts of C99 allowed in the kernel. -- With best wishes Dmitry
