Re: [PATCH v2 11/21] drm/i915/dp: Add way to get active pipes with syncing commits

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

On Fri, Feb 23, 2024 at 11:11:45PM +0200, Ville Syrjälä wrote:
> On Tue, Feb 20, 2024 at 11:18:31PM +0200, Imre Deak wrote:
> > Add a way to get the active pipes through a given DP port by syncing
> > against a related pending non-blocking commit. Atm
> > intel_dp_get_active_pipes() will only try to sync a given pipe and if
> > that would block ignore the pipe. A follow-up change enabling the DP
> > tunnel BW allocation mode will need to ensure that all active pipes are
> > returned.
> > 
> > This change will use intel_crtc_state::uapi.commit instead of the
> > corresponding commit in the connector state. This shouldn't make a
> > difference, since the two commit objects match for an active pipe.
> 
> There is a slight difference here in that a non-modeset/fastset commit
> will not have the connector inluded in the state and thus
> connector->state.commit will be updated.
> 
> I think the original idea of the code was to just skip anything that
> looks like it's already undergoing a full modeset. With this we might
> skip the retrain if there happens to be any kind of commit happening
> on the crtc. Althoguh it seems that the original code is already
> broken in the same way when there's a fastset happening in parallel.

Ok, didn't think of it. Are you ok to sync instead of try-sync the pipes
in case of link re-training?

> > A follow-up patchset will remove syncing during TC port reset, which
> > should reset a port/pipe even if syncing against a commit would block.
> > Syncing OTOH is not needed there, since the commit used for the reset
> > implies a sync already. For now add a TODO comment for this.
> > 
> > v2:
> > - Add a separate function to try-sync the pipes. (Ville)
> > 
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_crtc.c | 27 +++++++++++++++++++++++
> >  drivers/gpu/drm/i915/display/intel_crtc.h |  1 +
> >  drivers/gpu/drm/i915/display/intel_dp.c   |  6 ++---
> >  drivers/gpu/drm/i915/display/intel_tc.c   |  7 ++++++
> >  4 files changed, 37 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c
> > index 25593f6aae7de..17ed2e62cc66a 100644
> > --- a/drivers/gpu/drm/i915/display/intel_crtc.c
> > +++ b/drivers/gpu/drm/i915/display/intel_crtc.c
> > @@ -654,3 +654,30 @@ void intel_pipe_update_end(struct intel_atomic_state *state,
> >  out:
> >  	intel_psr_unlock(new_crtc_state);
> >  }
> > +
> > +/**
> > + * intel_crtc_try_sync_pipes - Try syncing pending commits on a set of pipes
> > + * @i915: i915 device object
> > + * @pipe_mask: Mask of pipes to sync
> > + *
> > + * Try to sync a pending non-blocking commit for the provided pipes in
> > + * @pipe_mask. The commit won't be synced if this would block.
> > + *
> > + * Return a mask of the pipes that got synced or didn't need syncing.
> > + */
> > +u32 intel_crtc_try_sync_pipes(struct drm_i915_private *i915, u32 pipe_mask)
> > +{
> > +	struct intel_crtc *crtc;
> > +	u32 synced = 0;
> > +
> > +	for_each_intel_crtc_in_pipe_mask(&i915->drm, crtc, pipe_mask) {
> > +		const struct intel_crtc_state *crtc_state =
> > +			to_intel_crtc_state(crtc->base.state);
> > +
> > +		if (!crtc_state->uapi.commit ||
> > +		    try_wait_for_completion(&crtc_state->uapi.commit->hw_done))
> > +			synced |= BIT(crtc->pipe);
> > +	}
> > +
> > +	return synced;
> > +}
> > diff --git a/drivers/gpu/drm/i915/display/intel_crtc.h b/drivers/gpu/drm/i915/display/intel_crtc.h
> > index 22d7993d1f0ba..71a5b93166da7 100644
> > --- a/drivers/gpu/drm/i915/display/intel_crtc.h
> > +++ b/drivers/gpu/drm/i915/display/intel_crtc.h
> > @@ -47,5 +47,6 @@ struct intel_crtc *intel_crtc_for_pipe(struct drm_i915_private *i915,
> >  void intel_wait_for_vblank_if_active(struct drm_i915_private *i915,
> >  				     enum pipe pipe);
> >  void intel_crtc_wait_for_next_vblank(struct intel_crtc *crtc);
> > +u32 intel_crtc_try_sync_pipes(struct drm_i915_private *i915, u32 pipe_mask);
> >  
> >  #endif
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> > index d9e75922ff8f5..d0452d3e534a7 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -5048,10 +5048,6 @@ int intel_dp_get_active_pipes(struct intel_dp *intel_dp,
> >  		if (!crtc_state->hw.active)
> >  			continue;
> >  
> > -		if (conn_state->commit &&
> > -		    !try_wait_for_completion(&conn_state->commit->hw_done))
> > -			continue;
> > -
> >  		*pipe_mask |= BIT(crtc->pipe);
> >  	}
> >  	drm_connector_list_iter_end(&conn_iter);
> > @@ -5091,6 +5087,8 @@ int intel_dp_retrain_link(struct intel_encoder *encoder,
> >  	if (ret)
> >  		return ret;
> >  
> > +	pipe_mask &= intel_crtc_try_sync_pipes(dev_priv, pipe_mask);
> > +
> >  	if (pipe_mask == 0)
> >  		return 0;
> >  
> > diff --git a/drivers/gpu/drm/i915/display/intel_tc.c b/drivers/gpu/drm/i915/display/intel_tc.c
> > index 6b374d481cd9e..14d17903a81f5 100644
> > --- a/drivers/gpu/drm/i915/display/intel_tc.c
> > +++ b/drivers/gpu/drm/i915/display/intel_tc.c
> > @@ -7,6 +7,7 @@
> >  #include "i915_reg.h"
> >  #include "intel_atomic.h"
> >  #include "intel_cx0_phy_regs.h"
> > +#include "intel_crtc.h"
> >  #include "intel_ddi.h"
> >  #include "intel_de.h"
> >  #include "intel_display.h"
> > @@ -1663,6 +1664,12 @@ static int reset_link_commit(struct intel_tc_port *tc,
> >  	if (ret)
> >  		return ret;
> >  
> > +	/*
> > +	 * TODO: remove the following, since an output must be reset
> > +	 * even if we had to wait for a non-blocking commit on a pipe.
> > +	 */
> > +	pipe_mask &= intel_crtc_try_sync_pipes(i915, pipe_mask);
> > +
> >  	if (!pipe_mask)
> >  		return 0;
> >  
> > -- 
> > 2.39.2
> 
> -- 
> Ville Syrjälä
> Intel