Re: [PATCH v5] drm/i915: Handle drm-layer errors in intel_dp_add_mst_connector

James Ausmus
2017-10-17T16:45:47Z

On Tue, Oct 17, 2017 at 06:38:18PM +0300, Ville Syrjälä wrote:
> On Fri, Oct 13, 2017 at 11:01:44AM -0700, James Ausmus wrote:
> > Make intel_dp_add_mst_connector handle error returns from the drm_ calls.
> > Add intel_connector_free to support cleanup on the error path.
> >
> > v2: Rename new function to avoid confusion, and simplify error
> > paths (Ville)
> >
> > v3: Indentation fixup, style fixes (Ville)
> >
> > v4: Clarify usage of intel_connector_free, and fix usage of
> > intel_connector_free
> >
> > v5: Rebase
> >
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Signed-off-by: James Ausmus <james.ausmus@intel.com>
>
> Pushed to dinq. Thanks for the patch.
>
> One slight concern that came to my mind is whether we'll leave sufficient
> breadcrumbs into the log to see that we failed to add a connector that
> was really meant to be there. We might want to add some error prints
> for that.

Hmm - looking at the drm_dp_mst_topology_mgr bits, it looks like if
add_connector returns null, the port in question is just dropped
silently. I'll put adding some error messages on failure to my TODO
list. :)

Thanks!

-James

>
> > ---
> > drivers/gpu/drm/i915/intel_display.c | 13 +++++++++++++
> > drivers/gpu/drm/i915/intel_dp_mst.c | 27 +++++++++++++++++++++++----
> > drivers/gpu/drm/i915/intel_drv.h | 1 +
> > 3 files changed, 37 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 185be5726b5e..796ead425f23 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -6139,6 +6139,19 @@ struct intel_connector *intel_connector_alloc(void)
> > return connector;
> > }
> >
> > +/*
> > + * Free the bits allocated by intel_connector_alloc.
> > + * This should only be used after intel_connector_alloc has returned
> > + * successfully, and before drm_connector_init returns successfully.
> > + * Otherwise the destroy callbacks for the connector and the state should
> > + * take care of proper cleanup/free
> > + */
> > +void intel_connector_free(struct intel_connector *connector)
> > +{
> > + kfree(to_intel_digital_connector_state(connector->base.state));
> > + kfree(connector);
> > +}
> > +
> > /* Simple connector->get_hw_state implementation for encoders that support only
> > * one connector and no cloning and hence the encoder state determines the state
> > * of the connector. */
> > diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
> > index f7c782576162..772521440a9f 100644
> > --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> > +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> > @@ -458,13 +458,20 @@ static struct drm_connector *intel_dp_add_mst_connector(struct drm_dp_mst_topolo
> > struct intel_connector *intel_connector;
> > struct drm_connector *connector;
> > enum pipe pipe;
> > + int ret;
> >
> > intel_connector = intel_connector_alloc();
> > if (!intel_connector)
> > return NULL;
> >
> > connector = &intel_connector->base;
> > - drm_connector_init(dev, connector, &intel_dp_mst_connector_funcs, DRM_MODE_CONNECTOR_DisplayPort);
> > + ret = drm_connector_init(dev, connector, &intel_dp_mst_connector_funcs,
> > + DRM_MODE_CONNECTOR_DisplayPort);
> > + if (ret) {
> > + intel_connector_free(intel_connector);
> > + return NULL;
> > + }
> > +
> > drm_connector_helper_add(connector, &intel_dp_mst_connector_helper_funcs);
> >
> > intel_connector->get_hw_state = intel_dp_mst_get_hw_state;
> > @@ -472,15 +479,27 @@ static struct drm_connector *intel_dp_add_mst_connector(struct drm_dp_mst_topolo
> > intel_connector->port = port;
> >
> > for_each_pipe(dev_priv, pipe) {
> > - drm_mode_connector_attach_encoder(&intel_connector->base,
> > - &intel_dp->mst_encoders[pipe]->base.base);
> > + struct drm_encoder *enc =
> > + &intel_dp->mst_encoders[pipe]->base.base;
> > +
> > + ret = drm_mode_connector_attach_encoder(&intel_connector->base,
> > + enc);
> > + if (ret)
> > + goto err;
> > }
> >
> > drm_object_attach_property(&connector->base, dev->mode_config.path_property, 0);
> > drm_object_attach_property(&connector->base, dev->mode_config.tile_property, 0);
> >
> > - drm_mode_connector_set_path_property(connector, pathprop);
> > + ret = drm_mode_connector_set_path_property(connector, pathprop);
> > + if (ret)
> > + goto err;
> > +
> > return connector;
> > +
> > +err:
> > + drm_connector_cleanup(connector);
> > + return NULL;
> > }
> >
> > static void intel_dp_register_mst_connector(struct drm_connector *connector)
> > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> > index d61985f93d40..f863a0ca39d9 100644
> > --- a/drivers/gpu/drm/i915/intel_drv.h
> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > @@ -1363,6 +1363,7 @@ void intel_pps_unlock_regs_wa(struct drm_i915_private *dev_priv);
> > void intel_encoder_destroy(struct drm_encoder *encoder);
> > int intel_connector_init(struct intel_connector *);
> > struct intel_connector *intel_connector_alloc(void);
> > +void intel_connector_free(struct intel_connector *connector);
> > bool intel_connector_get_hw_state(struct intel_connector *connector);
> > void intel_connector_attach_encoder(struct intel_connector *connector,
> > struct intel_encoder *encoder);
> > --
> > 2.14.1
>
> --
> Ville Syrjälä
> Intel OTC