Re: [PATCH] drm/radeon: add late_register for connector

[Alex Deucher]

+ Hans

On Thu, Oct 3, 2024 at 2:33 AM Wu Hoi Pok <wuhoipok@xxxxxxxxx> wrote:
>
> This is a fix patch not tested yet,
> for a bug I introduce in previous rework of radeon driver.
> The bug is a null dereference in 'aux.dev', which is the
> 'device' not registered, resulting in kernel panic. By having
> 'late_register', the connector should be registered after
> 'drm_dev_register' automatically.
>
> Please help testing thank you.
>
> Signed-off-by: Wu Hoi Pok <wuhoipok@xxxxxxxxx>
> ---
>  drivers/gpu/drm/radeon/atombios_dp.c       |  9 ++-------
>  drivers/gpu/drm/radeon/radeon_connectors.c | 17 +++++++++++++++++
>  2 files changed, 19 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
> index fca8b08535a5..6328627b7c34 100644
> --- a/drivers/gpu/drm/radeon/atombios_dp.c
> +++ b/drivers/gpu/drm/radeon/atombios_dp.c
> @@ -228,10 +228,8 @@ void radeon_dp_aux_init(struct radeon_connector *radeon_connector)
>  {
>         struct drm_device *dev = radeon_connector->base.dev;
>         struct radeon_device *rdev = dev->dev_private;
> -       int ret;
>
>         radeon_connector->ddc_bus->rec.hpd = radeon_connector->hpd.hpd;
> -       radeon_connector->ddc_bus->aux.dev = radeon_connector->base.kdev;
>         radeon_connector->ddc_bus->aux.drm_dev = radeon_connector->base.dev;
>         if (ASIC_IS_DCE5(rdev)) {
>                 if (radeon_auxch)
> @@ -242,11 +240,8 @@ void radeon_dp_aux_init(struct radeon_connector *radeon_connector)
>                 radeon_connector->ddc_bus->aux.transfer = radeon_dp_aux_transfer_atom;
>         }
>
> -       ret = drm_dp_aux_register(&radeon_connector->ddc_bus->aux);
> -       if (!ret)
> -               radeon_connector->ddc_bus->has_aux = true;
> -
> -       WARN(ret, "drm_dp_aux_register() failed with error %d\n", ret);
> +       drm_dp_aux_init(&radeon_connector->ddc_bus->aux);
> +       radeon_connector->ddc_bus->has_aux = true;
>  }
>
>  /***** general DP utility functions *****/
> diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
> index 528a8f3677c2..f9c73c55f04f 100644
> --- a/drivers/gpu/drm/radeon/radeon_connectors.c
> +++ b/drivers/gpu/drm/radeon/radeon_connectors.c
> @@ -1786,6 +1786,20 @@ static enum drm_mode_status radeon_dp_mode_valid(struct drm_connector *connector
>         return MODE_OK;
>  }
>
> +static int
> +radeon_connector_late_register(struct drm_connector *connector)
> +{
> +       struct radeon_connector *radeon_connector = to_radeon_connector(connector);
> +       int r = 0;
> +
> +       if (radeon_connector->ddc_bus->has_aux) {
> +               radeon_connector->ddc_bus->aux.dev = radeon_connector->base.kdev;
> +               r = drm_dp_aux_register(&radeon_connector->ddc_bus->aux);
> +       }
> +
> +       return r;
> +}
> +
>  static const struct drm_connector_helper_funcs radeon_dp_connector_helper_funcs = {
>         .get_modes = radeon_dp_get_modes,
>         .mode_valid = radeon_dp_mode_valid,
> @@ -1800,6 +1814,7 @@ static const struct drm_connector_funcs radeon_dp_connector_funcs = {
>         .early_unregister = radeon_connector_unregister,
>         .destroy = radeon_connector_destroy,
>         .force = radeon_dvi_force,
> +       .late_register = radeon_connector_late_register,
>  };
>
>  static const struct drm_connector_funcs radeon_edp_connector_funcs = {
> @@ -1810,6 +1825,7 @@ static const struct drm_connector_funcs radeon_edp_connector_funcs = {
>         .early_unregister = radeon_connector_unregister,
>         .destroy = radeon_connector_destroy,
>         .force = radeon_dvi_force,
> +       .late_register = radeon_connector_late_register,
>  };
>
>  static const struct drm_connector_funcs radeon_lvds_bridge_connector_funcs = {
> @@ -1820,6 +1836,7 @@ static const struct drm_connector_funcs radeon_lvds_bridge_connector_funcs = {
>         .early_unregister = radeon_connector_unregister,
>         .destroy = radeon_connector_destroy,
>         .force = radeon_dvi_force,
> +       .late_register = radeon_connector_late_register,
>  };
>
>  void
> --
> 2.46.2
>