On 1/15/26 8:29 AM, Dmitry Baryshkov wrote:
> From: Jessica Zhang <[email protected]>
>
> Instead of relying on the link_ready flag to specify if DP is connected,
> read the DPCD bits and get the sink count to accurately detect if DP is
> connected.
>
> Signed-off-by: Jessica Zhang <[email protected]>
> Signed-off-by: Dmitry Baryshkov <[email protected]>
> ---
> drivers/gpu/drm/msm/dp/dp_display.c | 60
> +++++++++++++++++++++++++++++++++++++
> drivers/gpu/drm/msm/dp/dp_drm.c | 20 -------------
> drivers/gpu/drm/msm/dp/dp_drm.h | 2 ++
> 3 files changed, 62 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c
> b/drivers/gpu/drm/msm/dp/dp_display.c
> index 5997cd28ba11..a05144de3b93 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -1151,6 +1151,66 @@ static int msm_dp_hpd_event_thread_start(struct
> msm_dp_display_private *msm_dp_p
> return 0;
> }
>
> +/**
> + * msm_dp_bridge_detect - callback to determine if connector is connected
> + * @bridge: Pointer to drm bridge structure
> + * @connector: Pointer to drm connector structure
> + * Returns: Bridge's 'is connected' status
> + */
> +enum drm_connector_status msm_dp_bridge_detect(struct drm_bridge *bridge,
> + struct drm_connector *connector)
> +{
> + struct msm_dp_bridge *msm_dp_bridge = to_dp_bridge(bridge);
> + struct msm_dp *dp = msm_dp_bridge->msm_dp_display;
> + struct msm_dp_display_private *priv;
> + int ret = 0;
> + int status = connector_status_disconnected;
> + u8 dpcd[DP_RECEIVER_CAP_SIZE];
> + struct drm_dp_desc desc;
Reverse-Christmas-tree would be nice
> +
> + dp = to_dp_bridge(bridge)->msm_dp_display;
> +
> + priv = container_of(dp, struct msm_dp_display_private, msm_dp_display);
> +
> + if (!dp->link_ready)
> + return status;
> +
> + msm_dp_aux_enable_xfers(priv->aux, true);
> +
> + ret = pm_runtime_resume_and_get(&dp->pdev->dev);
> + if (ret) {
See ef8057b07c72 ("PM: runtime: Wrapper macros for ACQUIRE()/ACQUIRE_ERR()")
> + DRM_ERROR("failed to pm_runtime_resume\n");
> + msm_dp_aux_enable_xfers(priv->aux, false);
> + return status;
> + }
> +
> + ret = msm_dp_aux_is_link_connected(priv->aux);
> + if (dp->internal_hpd && !ret)
> + goto end;
> +
> + ret = drm_dp_read_dpcd_caps(priv->aux, dpcd);
> + if (ret)
> + goto end;
> +
> + ret = drm_dp_read_desc(priv->aux, &desc, drm_dp_is_branch(dpcd));
> + if (ret)
> + goto end;
> +
> + status = connector_status_connected;
> + if (drm_dp_read_sink_count_cap(connector, dpcd, &desc)) {
> + int sink_count = drm_dp_read_sink_count(priv->aux);
> +
> + drm_dbg_dp(dp->drm_dev, "sink_count = %d\n", sink_count);
> +
> + if (sink_count <= 0)
> + status = connector_status_disconnected;
< 0 would be an error coming from drm_dp_dpcd_read_byte, should we log
it?
Konrad
