On Fri, Jan 09, 2026 at 10:06:29AM +0100, Konrad Dybcio wrote:
> Dmitry, would it be beneficial to throw an actual error when the rate is
> is mangled? i.e.
This certainly seems more robust if acceptable.
> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> index aa2303d0e148..4f710b8e6bc6 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> @@ -2404,9 +2404,9 @@ static int msm_dp_ctrl_link_retrain(struct
> msm_dp_ctrl_private *ctrl)
> return msm_dp_ctrl_setup_main_link(ctrl, &training_step);
> }
>
> -static void msm_dp_ctrl_config_msa(struct msm_dp_ctrl_private *ctrl,
> - u32 rate, u32 stream_rate_khz,
> - bool is_ycbcr_420)
> +static int msm_dp_ctrl_config_msa(struct msm_dp_ctrl_private *ctrl,
> + u32 rate, u32 stream_rate_khz,
> + bool is_ycbcr_420)
> {
> u32 pixel_m, pixel_n;
> u32 mvid, nvid, pixel_div = 0, dispcc_input_rate;
This initialization is now unnecessary with this change.
> @@ -2415,14 +2415,21 @@ static void msm_dp_ctrl_config_msa(struct
> msm_dp_ctrl_private *ctrl,
> u32 const link_rate_hbr3 = 810000;
> unsigned long den, num;
>
> - if (rate == link_rate_hbr3)
> + switch (rate) {
> + case link_rate_hbr3:
> pixel_div = 6;
> - else if (rate == 162000 || rate == 270000)
> - pixel_div = 2;
> - else if (rate == link_rate_hbr2)
> + break;
> + case link_rate_hbr2:
> pixel_div = 4;
> - else
> + break;
> + case 270000:
> + case 162000:
> + pixel_div = 2;
> + break;
> + default:
> DRM_ERROR("Invalid pixel mux divider\n");
> + return -EINVAL;
> + }
>
> dispcc_input_rate = (rate * 10) / pixel_div;
>
> @@ -2458,6 +2465,8 @@ static void msm_dp_ctrl_config_msa(struct
> msm_dp_ctrl_private *ctrl,
> drm_dbg_dp(ctrl->drm_dev, "mvid=0x%x, nvid=0x%x\n", mvid, nvid);
> msm_dp_write_link(ctrl, REG_DP_SOFTWARE_MVID, mvid);
> msm_dp_write_link(ctrl, REG_DP_SOFTWARE_NVID, nvid);
> +
> + return 0;
> }
>
> int msm_dp_ctrl_on_stream(struct msm_dp_ctrl *msm_dp_ctrl, bool
> force_link_train)
> @@ -2525,10 +2534,11 @@ int msm_dp_ctrl_on_stream(struct msm_dp_ctrl
> *msm_dp_ctrl, bool force_link_train
>
> msm_dp_ctrl_configure_source_params(ctrl);
>
> - msm_dp_ctrl_config_msa(ctrl,
> - ctrl->link->link_params.rate,
> - pixel_rate_orig,
> - ctrl->panel->msm_dp_mode.out_fmt_is_yuv_420);
> + ret = msm_dp_ctrl_config_msa(ctrl, ctrl->link->link_params.rate,
> + pixel_rate_orig,
> +
> ctrl->panel->msm_dp_mode.out_fmt_is_yuv_420);
> + if (ret)
> + return ret;
>
> msm_dp_panel_clear_dsc_dto(ctrl->panel);
>
>
>
> Konrad
