> -----Original Message-----
> From: Deak, Imre <[email protected]>
> Sent: Friday, March 20, 2026 2:59 PM
> To: [email protected]; [email protected]
> Cc: Shankar, Uma <[email protected]>; Ville Syrjälä
> <[email protected]>; [email protected]
> Subject: [PATCH] drm/i915/dp_tunnel: Fix error handling when clearing stream
> BW
> in atomic state
>
> 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 <[email protected]>
> Cc: Ville Syrjälä <[email protected]>
> Cc: <[email protected]> # v6.9+
> Fixes: a4efae87ecb2 ("drm/i915/dp: Compute DP tunnel BW during encoder state
> computation")
> Signed-off-by: Imre Deak <[email protected]>
> ---
> drivers/gpu/drm/i915/display/intel_display.c | 8 +++++++-
> .../gpu/drm/i915/display/intel_dp_tunnel.c | 20 +++++++++++++------
> .../gpu/drm/i915/display/intel_dp_tunnel.h | 11 ++++++----
> 3 files changed, 28 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> b/drivers/gpu/drm/i915/display/intel_display.c
> index ee501009a251f..882db77c0bbcd 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -4640,6 +4640,7 @@ intel_crtc_prepare_cleared_state(struct
> intel_atomic_state *state,
> 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)
> @@ -4648,7 +4649,12 @@ intel_crtc_prepare_cleared_state(struct
> intel_atomic_state *state,
> /* 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 diff
> --git
> a/drivers/gpu/drm/i915/display/intel_dp_tunnel.c
> b/drivers/gpu/drm/i915/display/intel_dp_tunnel.c
> index 1fd1ac8d556d8..7363c98172971 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_tunnel.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_tunnel.c
> @@ -659,19 +659,27 @@ int intel_dp_tunnel_atomic_compute_stream_bw(struct
> intel_atomic_state *state,
> *
> * 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);
Hi Imre,
Should we not drop reference even in case of failure, is this intentional ?
Regards,
Uma Shankar
> +
> + return 0;
> }
>
> /**
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_tunnel.h
> b/drivers/gpu/drm/i915/display/intel_dp_tunnel.h
> index 7f0f720e8dcad..10ab9eebcef69 100644
> --- 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_stream_bw(struct
> intel_atomic_state *state,
> 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(struct
> intel_atomic_state *state,
> 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,
> --
> 2.49.1
