On 09/08/2025 03:35, Jessica Zhang wrote:
> 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 <jessica.zhang@oss.qualcomm.com>
> ---
> drivers/gpu/drm/msm/dp/dp_display.c | 54 +++++++++++++++++++++++++++++++++++++
> drivers/gpu/drm/msm/dp/dp_drm.c | 18 -------------
> drivers/gpu/drm/msm/dp/dp_drm.h | 1 +
> 3 files changed, 55 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index bfcb39ff89e0..e2556de99894 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -1142,6 +1142,60 @@ 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
> + * Returns: Bridge's 'is connected' status
> + */
> +enum drm_connector_status msm_dp_bridge_detect(struct drm_bridge *bridge)
> +{
> + 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, sink_count = 0;
> + int status = connector_status_disconnected;
> + u8 dpcd[DP_RECEIVER_CAP_SIZE];
> +
> + 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) {
> + 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;
> +
> + sink_count = drm_dp_read_sink_count(priv->aux);
Should be guarded by drm_dp_read_sink_count_cap()
> +
> + drm_dbg_dp(dp->drm_dev, "is_branch = %s, sink_count = %d\n",
> + str_true_false(drm_dp_is_branch(dpcd)),
> + sink_count);
> +
> + if (drm_dp_is_branch(dpcd) && sink_count == 0)
> + status = connector_status_disconnected;
> + else
> + status = connector_status_connected;
> +
> +end:
> + pm_runtime_put_sync(&dp->pdev->dev);
> + return status;
> +}
> +
> static irqreturn_t msm_dp_display_irq_handler(int irq, void *dev_id)
> {
> struct msm_dp_display_private *dp = dev_id;
> diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c b/drivers/gpu/drm/msm/dp/dp_drm.c
> index f222d7ccaa88..e4622c85fb66 100644
> --- a/drivers/gpu/drm/msm/dp/dp_drm.c
> +++ b/drivers/gpu/drm/msm/dp/dp_drm.c
> @@ -15,24 +15,6 @@
> #include "dp_audio.h"
> #include "dp_drm.h"
>
> -/**
> - * msm_dp_bridge_detect - callback to determine if connector is connected
> - * @bridge: Pointer to drm bridge structure
> - * Returns: Bridge's 'is connected' status
> - */
> -static enum drm_connector_status msm_dp_bridge_detect(struct drm_bridge *bridge)
> -{
> - struct msm_dp *dp;
> -
> - dp = to_dp_bridge(bridge)->msm_dp_display;
> -
> - drm_dbg_dp(dp->drm_dev, "link_ready = %s\n",
> - str_true_false(dp->link_ready));
> -
> - return (dp->link_ready) ? connector_status_connected :
> - connector_status_disconnected;
> -}
> -
> static int msm_dp_bridge_atomic_check(struct drm_bridge *bridge,
> struct drm_bridge_state *bridge_state,
> struct drm_crtc_state *crtc_state,
> diff --git a/drivers/gpu/drm/msm/dp/dp_drm.h b/drivers/gpu/drm/msm/dp/dp_drm.h
> index d8c9b905f8bf..0f0d4bacb194 100644
> --- a/drivers/gpu/drm/msm/dp/dp_drm.h
> +++ b/drivers/gpu/drm/msm/dp/dp_drm.h
> @@ -25,6 +25,7 @@ int msm_dp_bridge_init(struct msm_dp *msm_dp_display, struct drm_device *dev,
> struct drm_encoder *encoder,
> bool yuv_supported);
>
> +enum drm_connector_status msm_dp_bridge_detect(struct drm_bridge *bridge);
> void msm_dp_bridge_atomic_enable(struct drm_bridge *drm_bridge,
> struct drm_atomic_state *state);
> void msm_dp_bridge_atomic_disable(struct drm_bridge *drm_bridge,
>
--
With best wishes
Dmitry