On Fri, Jun 05, 2026 at 11:28:37PM +0200, Alexander Kaplan wrote:
> After a DP-alt sink is disconnected with the link still active,
> intel_tc_port_link_reset_work() tries to recover the link via a
> modeset, flagging the active CRTCs with connectors_changed in
> reset_link_commit(). By that point intel_dp_detect() has already
> reset the sink capabilities (EDID, dfp.*, DSC DPCD - see the FIXME in
> intel_dp_detect()), so the recovery modeset is computed without them.
> Depending on which capabilities the connected mode requires, this
> either fails the atomic check with -EINVAL, triggering the WARN in
> intel_tc_port_link_reset_work():
>
> i915 0000:00:02.0: [drm] drm_WARN_ON(ret)
> WARNING: ... at drivers/gpu/drm/i915/display/intel_tc.c:1838
> intel_tc_port_link_reset_work+0x38c/0x420
>
> or commits a configuration the disconnected link can't sustain: link
> training fails and the output is left enabled on the disconnected
> port. Either way the output stays enabled, keeping the TC PHY
> ownership held and the TC mode locked. AUX transfers then get
> rejected based on intel_digital_port_connected_locked(), so detecting
> a newly connected sink keeps failing as well: the port can't be
> recovered without disabling the output by some other means (in
> practice a reboot).
>
> Disable the affected outputs instead of modesetting them, matching
> how commit c598c335da42 ("drm/i915/tc: Reset TypeC PHYs left enabled
> in DP-alt mode after the sink disconnects") handles the equivalent
> situation during boot/resume sanitization, for the same reason. The
> disable also releases the PHY ownership synchronously - via the
> encoder's post-PLL-disable hook - avoiding the IOM/TCSS firmware
> timeout the above commit worked around, and unblocking the HPD status
> updates of other TypeC ports. The output gets re-enabled via the
> normal hotplug flow once a sink is connected again.
>
> Preserving the sink capabilities across the disconnect instead (the
> direction proposed for the DSC caps in the gitlab reports below)
> would avoid the -EINVAL, but not the second failure mode: the
> recovery modeset would still be committed against a dead link,
> leaving the enabled output behind after a failed link training.
> Disabling the output covers both.
>
> Observed on PTL with a DP-alt -> HDMI 2.1 PCON adapter on a TV power
> cycle (both failure modes above); reports with the matching WARN on
> ADL and MTL in the links below.
The driver cannot disable an output that userspace has enabled. The TC
port reset above should also result in a hotplug notification, which
userspace should handle reconfiguring and re-enabling the output as
needed. Could you please provide a dmesg log on the first Link: ticket
below with the rebased
https://gitlab.freedesktop.org/-/project/4519/uploads/326fe332d4e847b29c1f38907be171df/0001-drm-i915-dp-Fix-resetting-DSC-capability-during-dete.patch
applied on the lastest drm-tip kernel, booting with drm.debug=0x15e and
reproducing the problem you still observe (also mentioning the
reproducation steps)?
Thanks.
> Fixes: c598c335da42 ("drm/i915/tc: Reset TypeC PHYs left enabled in DP-alt
> mode after the sink disconnects")
> Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14807
> Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/11551
> Cc: Imre Deak <[email protected]>
> Cc: Ville Syrjälä <[email protected]>
> Signed-off-by: Alexander Kaplan <[email protected]>
> ---
> diff --git a/drivers/gpu/drm/i915/display/intel_tc.c
> b/drivers/gpu/drm/i915/display/intel_tc.c
> index a21dd4e3fe4c..ae9da59ca8e3 100644
> --- a/drivers/gpu/drm/i915/display/intel_tc.c
> +++ b/drivers/gpu/drm/i915/display/intel_tc.c
> @@ -5,6 +5,7 @@
>
> #include <linux/iopoll.h>
>
> +#include <drm/drm_atomic_uapi.h>
> #include <drm/drm_print.h>
>
> #include "intel_atomic.h"
> @@ -1764,9 +1765,13 @@ static int reset_link_commit(struct intel_tc_port *tc,
> struct intel_display *display = to_intel_display(tc->dig_port);
> struct intel_digital_port *dig_port = tc->dig_port;
> struct intel_dp *intel_dp = enc_to_intel_dp(&dig_port->base);
> + struct drm_connector_state *conn_state;
> + struct drm_connector *connector;
> + struct drm_plane_state *plane_state;
> + struct drm_plane *plane;
> struct intel_crtc *crtc;
> u8 pipe_mask;
> - int ret;
> + int i, ret;
>
> ret = drm_modeset_lock(&display->drm->mode_config.connection_mutex,
> ctx);
> if (ret)
> @@ -1779,6 +1784,13 @@ static int reset_link_commit(struct intel_tc_port *tc,
> if (!pipe_mask)
> return 0;
>
> + /*
> + * The sink is gone, so intel_dp_detect() has already reset the sink
> + * capabilities, and recomputing the config for the still active mode
> + * would fail (see the FIXME in intel_dp_detect()). Disable the
> + * outputs instead; the next sink connect re-enables them via the
> + * normal hotplug flow.
> + */
> for_each_intel_crtc_in_pipe_mask(display, crtc, pipe_mask) {
> struct intel_crtc_state *crtc_state;
>
> @@ -1786,7 +1798,33 @@ static int reset_link_commit(struct intel_tc_port *tc,
> if (IS_ERR(crtc_state))
> return PTR_ERR(crtc_state);
>
> - crtc_state->uapi.connectors_changed = true;
> + crtc_state->uapi.active = false;
> +
> + ret = drm_atomic_set_mode_prop_for_crtc(&crtc_state->uapi,
> NULL);
> + if (ret)
> + return ret;
> +
> + ret = drm_atomic_add_affected_planes(&state->base, &crtc->base);
> + if (ret)
> + return ret;
> +
> + ret = drm_atomic_add_affected_connectors(&state->base,
> &crtc->base);
> + if (ret)
> + return ret;
> + }
> +
> + for_each_new_connector_in_state(&state->base, connector, conn_state, i)
> {
> + ret = drm_atomic_set_crtc_for_connector(conn_state, NULL);
> + if (ret)
> + return ret;
> + }
> +
> + for_each_new_plane_in_state(&state->base, plane, plane_state, i) {
> + ret = drm_atomic_set_crtc_for_plane(plane_state, NULL);
> + if (ret)
> + return ret;
> +
> + drm_atomic_set_fb_for_plane(plane_state, NULL);
> }
>
> if (!__intel_tc_port_link_needs_reset(tc))
>
