nvidia-drm: trigger connector detect on hotplug events#1127
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kekiefer wants to merge 1 commit intoNVIDIA:mainfrom
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nvidia-drm: trigger connector detect on hotplug events#1127kekiefer wants to merge 1 commit intoNVIDIA:mainfrom
kekiefer wants to merge 1 commit intoNVIDIA:mainfrom
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When a DisplayPort sink is hotplugged after boot, the connector status reported in /sys/class/drm/card0-DP-1/status remains "disconnected" even though the kernel observes the HPD edge and emits a HOTPLUG=1 uevent. Userspace must run `echo detect > status` to refresh the connector before a modeset succeeds. The hotplug work handler nv_drm_handle_hotplug_event() was calling drm_kms_helper_hotplug_event(), which only sends a uevent and invokes the output_poll_changed callback. It never calls connector->detect(). Because the connector status is therefore never refreshed, DRM core keeps reporting the cached "disconnected" state. Call drm_helper_hpd_irq_event() instead. That helper iterates all DRM_CONNECTOR_POLL_HPD-flagged connectors, runs connector->detect() on each, updates the recorded status, and only sends the uevent if the status actually changed. This is the correct entry point for an HPD-edge notification and produces a fresh status read for userspace without requiring a manual detect. Signed-off-by: Kurt Kiefer <kekiefer@gmail.com>
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Note that this fix was developed and validated against a Jetson Orin AGX 64GB running the r36.5 fork of these kernel modules (https://gitlab.com/nvidia/nv-tegra/tegra/kernel-src/nv-kernel-display-driver/-/tree/l4t/l4t-r36.5) where there is no meaningful commit history, so submission there did not seem appropriate.
As such, this change was rebased to upstream here, but could not be revalidated.
Also, if this repository is not the appropriate upstream target, please let me know and I can redirect this patch.
When a DisplayPort sink is hotplugged after boot, the connector status reported in /sys/class/drm/card0-DP-1/status remains "disconnected" even though the kernel observes the HPD edge and emits a HOTPLUG=1 uevent. Userspace must run
echo detect > statusto refresh the connector before a modeset succeeds.The hotplug work handler nv_drm_handle_hotplug_event() was calling drm_kms_helper_hotplug_event(), which only sends a uevent and invokes the output_poll_changed callback. It never calls connector->detect(). Because the connector status is therefore never refreshed, DRM core keeps reporting the cached "disconnected" state.
Call drm_helper_hpd_irq_event() instead. That helper iterates all DRM_CONNECTOR_POLL_HPD-flagged connectors, runs connector->detect() on each, updates the recorded status, and only sends the uevent if the status actually changed. This is the correct entry point for an HPD-edge notification and produces a fresh status read for userspace without requiring a manual detect.