Re: [PATCH v3] drm/i915: clear CRTC color blob pointers after dropping refs

[Imre Deak]

On Fri, Jun 12, 2026 at 05:27:11PM +0300, Imre Deak wrote:
> On Fri, Jun 12, 2026 at 11:53:10AM +0800, Guangshuo Li wrote:
> > intel_crtc_put_color_blobs() 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@xxxxxxxxx>
> > Signed-off-by: Guangshuo Li <lgs201920130244@xxxxxxxxx>
> 
> Looks ok to me, thanks for the fix:
> Reviewed-by: Imre Deak <imre.deak@xxxxxxxxx>

Patch is pushed to drm-intel-next, thanks.

> 
> > ---
> > v3:
> >   - Move the blob pointer clearing to the end of
> >     intel_crtc_put_color_blobs(), as suggested by Imre.
> > 
> > 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..a16e1cb7d41e 100644
> > --- a/drivers/gpu/drm/i915/display/intel_atomic.c
> > +++ b/drivers/gpu/drm/i915/display/intel_atomic.c
> > @@ -289,6 +289,12 @@ static void intel_crtc_put_color_blobs(struct intel_crtc_state *crtc_state)
> >  
> >  	drm_property_blob_put(crtc_state->pre_csc_lut);
> >  	drm_property_blob_put(crtc_state->post_csc_lut);
> > +
> > +	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;
> >  }
> >  
> >  void intel_crtc_free_hw_state(struct intel_crtc_state *crtc_state)
> > -- 
> > 2.43.0
> >