[PATCH 6.18 235/309] drm/i915/dp_tunnel: Fix error handling when clearing stream BW in atomic state

Greg Kroah-Hartman
2026-03-31T17:07:05Z

From: Imre Deak <imre.deak@intel.com>

commit 77fcf58df15edcf3f5b5421f24814fb72796def9 upstream.

Clearing the DP tunnel stream BW in the atomic state involves getting
the tunnel group state, which can fail. Handle the error accordingly.

This fixes at least one issue where drm_dp_tunnel_atomic_set_stream_bw()
failed to get the tunnel group state returning -EDEADLK, which wasn't
handled. This lead to the ctx->contended warn later in modeset_lock()
while taking a WW mutex for another object in the same atomic state, and
thus within the same already contended WW context.

Moving intel_crtc_state_alloc() later would avoid freeing saved_state on
the error path; this stable patch leaves that simplification for a
follow-up.

Cc: Uma Shankar <uma.shankar@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: <stable@vger.kernel.org> # v6.9+
Fixes: a4efae87ecb2 ("drm/i915/dp: Compute DP tunnel BW during encoder state computation")
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/7617
Reviewed-by: Michał Grzelak <michal.grzelak@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20260320092900.13210-1-imre.deak@intel.com
(cherry picked from commit fb69d0076e687421188bc8103ab0e8e5825b1df1)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/i915/display/intel_display.c | 8 +++++++-
drivers/gpu/drm/i915/display/intel_dp_tunnel.c | 20 ++++++++++++++------
drivers/gpu/drm/i915/display/intel_dp_tunnel.h | 11 +++++++----
3 files changed, 28 insertions(+), 11 deletions(-)

--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -4568,6 +4568,7 @@ intel_crtc_prepare_cleared_state(struct
struct intel_crtc_state *crtc_state =
intel_atomic_get_new_crtc_state(state, crtc);
struct intel_crtc_state *saved_state;
+ int err;

saved_state = intel_crtc_state_alloc(crtc);
if (!saved_state)
@@ -4576,7 +4577,12 @@ intel_crtc_prepare_cleared_state(struct
/* free the old crtc_state->hw members */
intel_crtc_free_hw_state(crtc_state);

- intel_dp_tunnel_atomic_clear_stream_bw(state, crtc_state);
+ err = intel_dp_tunnel_atomic_clear_stream_bw(state, crtc_state);
+ if (err) {
+ kfree(saved_state);
+
+ return err;
+ }

/* FIXME: before the switch to atomic started, a new pipe_config was
* kzalloc'd. Code that depends on any field being zero should be
--- a/drivers/gpu/drm/i915/display/intel_dp_tunnel.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_tunnel.c
@@ -622,19 +622,27 @@ int intel_dp_tunnel_atomic_compute_strea
*
* Clear any DP tunnel stream BW requirement set by
* intel_dp_tunnel_atomic_compute_stream_bw().
+ *
+ * Returns 0 in case of success, a negative error code otherwise.
*/
-void intel_dp_tunnel_atomic_clear_stream_bw(struct intel_atomic_state *state,
- struct intel_crtc_state *crtc_state)
+int intel_dp_tunnel_atomic_clear_stream_bw(struct intel_atomic_state *state,
+ struct intel_crtc_state *crtc_state)
{
struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
+ int err;

if (!crtc_state->dp_tunnel_ref.tunnel)
- return;
+ return 0;
+
+ err = drm_dp_tunnel_atomic_set_stream_bw(&state->base,
+ crtc_state->dp_tunnel_ref.tunnel,
+ crtc->pipe, 0);
+ if (err)
+ return err;

- drm_dp_tunnel_atomic_set_stream_bw(&state->base,
- crtc_state->dp_tunnel_ref.tunnel,
- crtc->pipe, 0);
drm_dp_tunnel_ref_put(&crtc_state->dp_tunnel_ref);
+
+ return 0;
}

/**
--- a/drivers/gpu/drm/i915/display/intel_dp_tunnel.h
+++ b/drivers/gpu/drm/i915/display/intel_dp_tunnel.h
@@ -40,8 +40,8 @@ int intel_dp_tunnel_atomic_compute_strea
struct intel_dp *intel_dp,
const struct intel_connector *connector,
struct intel_crtc_state *crtc_state);
-void intel_dp_tunnel_atomic_clear_stream_bw(struct intel_atomic_state *state,
- struct intel_crtc_state *crtc_state);
+int intel_dp_tunnel_atomic_clear_stream_bw(struct intel_atomic_state *state,
+ struct intel_crtc_state *crtc_state);

int intel_dp_tunnel_atomic_add_state_for_crtc(struct intel_atomic_state *state,
struct intel_crtc *crtc);
@@ -88,9 +88,12 @@ intel_dp_tunnel_atomic_compute_stream_bw
return 0;
}

-static inline void
+static inline int
intel_dp_tunnel_atomic_clear_stream_bw(struct intel_atomic_state *state,
- struct intel_crtc_state *crtc_state) {}
+ struct intel_crtc_state *crtc_state)
+{
+ return 0;
+}

static inline int
intel_dp_tunnel_atomic_add_state_for_crtc(struct intel_atomic_state *state,