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

[Harry Wentland]

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.

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);
>  
>