[PATCH 13/15] drm/amdgpu/display: split dp connector registration (v3)

[Alex Deucher]

On Mon, Feb 24, 2020 at 4:09 PM Harry Wentland <hwentlan at amd.com> wrote:
>
> On 2020-02-07 4:17 p.m., Alex Deucher wrote:
> > Split into init and register functions to avoid a segfault
> > in some configs when the load/unload callbacks are removed.
> >
>
> Looks like MST is completely broken with this change with a NULL pointer
> dereference in drm_dp_aux_register.
>
> > v2:
> > - add back accidently dropped has_aux setting
> > - set dev in late_register
> >
> > v3:
> > - fix dp cec ordering
> >
> > Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
> > ---
> >  drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c   | 16 ++++++++++++++++
> >  drivers/gpu/drm/amd/amdgpu/atombios_dp.c         | 10 ++--------
> >  .../amd/display/amdgpu_dm/amdgpu_dm_mst_types.c  |  7 ++++++-
> >  3 files changed, 24 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
> > index ec1501e3a63a..f355d9a752d2 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
> > @@ -1461,6 +1461,20 @@ static enum drm_mode_status amdgpu_connector_dp_mode_valid(struct drm_connector
> >       return MODE_OK;
> >  }
> >
> > +static int
> > +amdgpu_connector_late_register(struct drm_connector *connector)
> > +{
> > +     struct amdgpu_connector *amdgpu_connector = to_amdgpu_connector(connector);
> > +     int r = 0;
> > +
> > +     if (amdgpu_connector->ddc_bus->has_aux) {
> > +             amdgpu_connector->ddc_bus->aux.dev = amdgpu_connector->base.kdev;
> > +             r = drm_dp_aux_register(&amdgpu_connector->ddc_bus->aux);
> > +     }
> > +
> > +     return r;
> > +}
> > +
> >  static const struct drm_connector_helper_funcs amdgpu_connector_dp_helper_funcs = {
> >       .get_modes = amdgpu_connector_dp_get_modes,
> >       .mode_valid = amdgpu_connector_dp_mode_valid,
> > @@ -1475,6 +1489,7 @@ static const struct drm_connector_funcs amdgpu_connector_dp_funcs = {
> >       .early_unregister = amdgpu_connector_unregister,
> >       .destroy = amdgpu_connector_destroy,
> >       .force = amdgpu_connector_dvi_force,
> > +     .late_register = amdgpu_connector_late_register,
> >  };
> >
> >  static const struct drm_connector_funcs amdgpu_connector_edp_funcs = {
> > @@ -1485,6 +1500,7 @@ static const struct drm_connector_funcs amdgpu_connector_edp_funcs = {
> >       .early_unregister = amdgpu_connector_unregister,
> >       .destroy = amdgpu_connector_destroy,
> >       .force = amdgpu_connector_dvi_force,
> > +     .late_register = amdgpu_connector_late_register,
> >  };
> >
> >  void
> > diff --git a/drivers/gpu/drm/amd/amdgpu/atombios_dp.c b/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
> > index ea702a64f807..9b74cfdba7b8 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
> > @@ -186,16 +186,10 @@ amdgpu_atombios_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *m
> >
> >  void amdgpu_atombios_dp_aux_init(struct amdgpu_connector *amdgpu_connector)
> >  {
> > -     int ret;
> > -
> >       amdgpu_connector->ddc_bus->rec.hpd = amdgpu_connector->hpd.hpd;
> > -     amdgpu_connector->ddc_bus->aux.dev = amdgpu_connector->base.kdev;
> >       amdgpu_connector->ddc_bus->aux.transfer = amdgpu_atombios_dp_aux_transfer;
> > -     ret = drm_dp_aux_register(&amdgpu_connector->ddc_bus->aux);
> > -     if (!ret)
> > -             amdgpu_connector->ddc_bus->has_aux = true;
> > -
> > -     WARN(ret, "drm_dp_aux_register_i2c_bus() failed with error %d\n", ret);
> > +     drm_dp_aux_init(&amdgpu_connector->ddc_bus->aux);
> > +     amdgpu_connector->ddc_bus->has_aux = true;
> >  }
> >
> >  /***** general DP utility functions *****/
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> > index 3959c942c88b..d5b9e72f2649 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> > @@ -155,6 +155,11 @@ amdgpu_dm_mst_connector_late_register(struct drm_connector *connector)
> >       struct amdgpu_dm_connector *amdgpu_dm_connector =
> >               to_amdgpu_dm_connector(connector);
> >       struct drm_dp_mst_port *port = amdgpu_dm_connector->port;
> > +     int r;
> > +
> > +     r = drm_dp_aux_register(&amdgpu_dm_connector->dm_dp_aux.aux);
>
> This calls drm_dp_aux_register_devnode which is also called later in
> drm_dp_mst_connector_late_register. Wonder if that's a problem.

Does this patch help?  I'm not too familiar with the MST code and I
don't have an MST monitor.

Alex


>
> Harry
>
> > +     if (r)
> > +             return r;
> >
> >  #if defined(CONFIG_DEBUG_FS)
> >       connector_debugfs_init(amdgpu_dm_connector);
> > @@ -484,7 +489,7 @@ void amdgpu_dm_initialize_dp_connector(struct amdgpu_display_manager *dm,
> >       aconnector->dm_dp_aux.aux.transfer = dm_dp_aux_transfer;
> >       aconnector->dm_dp_aux.ddc_service = aconnector->dc_link->ddc;
> >
> > -     drm_dp_aux_register(&aconnector->dm_dp_aux.aux);
> > +     drm_dp_aux_init(&aconnector->dm_dp_aux.aux);
> >       drm_dp_cec_register_connector(&aconnector->dm_dp_aux.aux,
> >                                     &aconnector->base);
> >
> >
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