Re: [PATCH v2] drm/i915: clear CRTC color blob pointers after dropping refs

[Imre Deak <imre.deak@intel.com>]

On Wed, Jun 10, 2026 at 11:54:19AM +0800, Guangshuo Li wrote:
> intel_crtc_free_hw_state() drops the CRTC color blob references, but
> leaves the corresponding pointers unchanged.
> 
> This can matter in intel_crtc_prepare_cleared_state(), which frees the
> old CRTC hw state before calling intel_dp_tunnel_atomic_clear_stream_bw().
> The latter can fail while looking up the DP tunnel group state, for
> example with -EDEADLK.
> 
> If that happens, the function returns without completing the cleared
> state preparation. The failed atomic state will then be cleared by the
> atomic core and intel_crtc_free_hw_state() can be called again for the
> same state, dropping the same blob references again.
> 
> Clear the blob pointers after dropping the references so repeated cleanup
> of the same CRTC hw state is safe.
> 
> Fixes: fb69d0076e68 ("drm/i915/dp_tunnel: Fix error handling when clearing stream BW in atomic state")
> Suggested-by: Imre Deak <imre.deak@intel.com>
> Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
> ---
> v2:
>   - Keep the original ordering in intel_crtc_prepare_cleared_state().
>   - Clear the blob reference pointers in intel_crtc_free_hw_state(), as
>     suggested by Imre.
> 
>  drivers/gpu/drm/i915/display/intel_atomic.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_atomic.c b/drivers/gpu/drm/i915/display/intel_atomic.c
> index 71b7325917b6..0cdae87e4bfc 100644
> --- a/drivers/gpu/drm/i915/display/intel_atomic.c
> +++ b/drivers/gpu/drm/i915/display/intel_atomic.c
> @@ -294,6 +294,12 @@ static void intel_crtc_put_color_blobs(struct intel_crtc_state *crtc_state)
>  void intel_crtc_free_hw_state(struct intel_crtc_state *crtc_state)
>  {
>  	intel_crtc_put_color_blobs(crtc_state);
> +
> +	crtc_state->hw.degamma_lut = NULL;
> +	crtc_state->hw.gamma_lut = NULL;
> +	crtc_state->hw.ctm = NULL;
> +	crtc_state->pre_csc_lut = NULL;
> +	crtc_state->post_csc_lut = NULL;
>  }

Could you still move the clearing closer where the refs are dropped, to
the end of intel_crtc_put_color_blobs()? Otherwise this looks ok to me.

>  
>  /**
> -- 
> 2.43.0
>