[PATCH] drm/radeon: on hotplug force link training to happen

[Jerome Glisse]

On Tue, Jul 17, 2012 at 6:25 PM, Alex Deucher <alexdeucher at gmail.com> wrote:
> On Tue, Jul 17, 2012 at 4:54 PM,  <j.glisse at gmail.com> wrote:
>> From: Jerome Glisse <jglisse at redhat.com>
>>
>> To have kernel behave like VGA/DVI we need to retrain link
>> on hotplug. For this to happen with need to report that
>> we need to link training to happen if we fail to get link
>> status and we need to force link training to happen by
>> setting connector dpms to off before asking it on.
>>
>> Signed-off-by: Jerome Glisse <jglisse at redhat.com>
>> ---
>>  drivers/gpu/drm/radeon/atombios_dp.c       |    2 +-
>>  drivers/gpu/drm/radeon/radeon_connectors.c |    7 +++++--
>>  2 files changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
>> index 5131b3b..7bb5d7e 100644
>> --- a/drivers/gpu/drm/radeon/atombios_dp.c
>> +++ b/drivers/gpu/drm/radeon/atombios_dp.c
>> @@ -670,7 +670,7 @@ bool radeon_dp_needs_link_train(struct radeon_connector *radeon_connector)
>>         struct radeon_connector_atom_dig *dig = radeon_connector->con_priv;
>>
>>         if (!radeon_dp_get_link_status(radeon_connector, link_status))
>> -               return false;
>> +               return true;
>
> I'm not sure we want to change the logic here.  The idea was that if
> we failed to get the link status, the monitor is most likely not
> attached so there's no need to retrain the link.
>
> Alex

Well not if you disconnect reconnect, the link goes down and link
status fails even with something connected. At least this is what i
get with couple different dp monitor

Cheers,
Jerome

>>         if (dp_channel_eq_ok(link_status, dig->dp_lane_count))
>>                 return false;
>>         return true;
>> diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
>> index 2914c57..4b42c9f 100644
>> --- a/drivers/gpu/drm/radeon/radeon_connectors.c
>> +++ b/drivers/gpu/drm/radeon/radeon_connectors.c
>> @@ -67,10 +67,13 @@ void radeon_connector_hotplug(struct drm_connector *connector)
>>                 int saved_dpms = connector->dpms;
>>
>>                 /* Only turn off the display it it's physically disconnected */
>> -               if (!radeon_hpd_sense(rdev, radeon_connector->hpd.hpd))
>> +               if (!radeon_hpd_sense(rdev, radeon_connector->hpd.hpd)) {
>>                         drm_helper_connector_dpms(connector, DRM_MODE_DPMS_OFF);
>> -               else if (radeon_dp_needs_link_train(radeon_connector))
>> +               } else if (radeon_dp_needs_link_train(radeon_connector)) {
>> +                       /* force a mode on to trigger dp link training */
>> +                       connector->dpms = DRM_MODE_DPMS_OFF;
>>                         drm_helper_connector_dpms(connector, DRM_MODE_DPMS_ON);
>> +               }
>>                 connector->dpms = saved_dpms;
>>         }
>>  }
>> --
>> 1.7.10.4
>>
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/dri-devel