On Mon, Jun 29, 2026 at 10:14:38PM +0800, Yongxing Mou wrote:
> In MST mode, multiple streams share the same DP link. Track a link_ready
> state so msm_dp_display_prepare_link() runs only once per link and
> repeated calls are skipped.
>
> Signed-off-by: Abhinav Kumar <[email protected]>
> Signed-off-by: Yongxing Mou <[email protected]>
> ---
> drivers/gpu/drm/msm/dp/dp_display.c | 42
> ++++++++++++++++++++++++-------------
> drivers/gpu/drm/msm/dp/dp_display.h | 1 +
> 2 files changed, 29 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c
> b/drivers/gpu/drm/msm/dp/dp_display.c
> index 2a74302bcb7c..d56ee10ee065 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -702,6 +702,9 @@ int msm_dp_display_prepare_link(struct msm_dp
> *msm_dp_display)
> if (msm_dp_display->is_edp)
> msm_dp_hpd_plug_handle(dp);
>
> + if (msm_dp_display->link_ready)
> + return 0;
> +
What kind of locking is protecting this variable? What prevents it from
being accessed concurrently?
> rc = pm_runtime_resume_and_get(&msm_dp_display->pdev->dev);
> if (rc) {
> DRM_ERROR("failed to pm_runtime_resume\n");
> @@ -714,14 +717,18 @@ int msm_dp_display_prepare_link(struct msm_dp
> *msm_dp_display)
> if (!msm_dp_display->active_stream_cnt) {
> msm_dp_display_host_phy_init(dp);
> force_link_train = true;
> +
> + rc = msm_dp_ctrl_on_link(dp->ctrl, dp->panel);
> + if (rc)
> + DRM_ERROR("Failed link training (rc=%d)\n", rc);
> + // TODO: schedule drm_connector_set_link_status_property()
> }
>
> - rc = msm_dp_ctrl_on_link(dp->ctrl, dp->panel);
> - if (rc)
> - DRM_ERROR("Failed link training (rc=%d)\n", rc);
> - // TODO: schedule drm_connector_set_link_status_property()
Why is it being moved now rather than in the patch where
active_stream_cnt was introduced?
> + rc = msm_dp_ctrl_prepare_stream_on(dp->ctrl, dp->panel,
> force_link_train);
> + if (!rc)
> + msm_dp_display->link_ready = true;
>
> - return msm_dp_ctrl_prepare_stream_on(dp->ctrl, dp->panel,
> force_link_train);
> + return rc;
> }
>
> static int msm_dp_display_enable(struct msm_dp_display_private *dp,
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.h
> b/drivers/gpu/drm/msm/dp/dp_display.h
> index 676213a48089..0464f8941e8d 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.h
> +++ b/drivers/gpu/drm/msm/dp/dp_display.h
> @@ -22,6 +22,7 @@ struct msm_dp {
> bool mst_active;
> unsigned int connector_type;
> bool is_edp;
> + bool link_ready;
Please group the status variables together.
>
> struct msm_dp_audio *msm_dp_audio;
> bool psr_supported;
>
> --
> 2.43.0
>
--
With best wishes
Dmitry
