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

[Hans de Goede]

Hi,

On 3-Oct-24 5:54 PM, Alex Deucher wrote:
> + 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>

Thank you both for the Cc and the patch. I can confirm that this
fixes the crash which I was seeing. Also IHMO this should have
a fixes tag for the original commit introducing the problem:

Fixes: 90985660ba48 ("drm/radeon: remove load callback from kms_driver")
Tested-by: Hans de Goede <hdegoede@xxxxxxxxxx>

Regards,

Hans





>> ---
>>  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
>>
>