[PATCH] drm/radeon/dp: check for errors in dpcd reads

[Sergei Antonov]

> Am 30.04.2014 um 15:58 schrieb Christian König <deathsimple at vodafone.de>:
> 
> Am 30.04.2014 15:27, schrieb Alex Deucher:
>> Check to make sure the transaction succeeded before
>> using the register value.  Fixes occasional link training
>> problems.
>> 
>> Noticed-by: Sergei Antonov <saproj at gmail.com>
>> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
> 
> Applied to my 3.15 queue.
> 
> Christian.

Why is not this patch still in Linus' tree? I looked forward to seeing it in 3.15-rc4 but it is not there.

> 
>> ---
>>  drivers/gpu/drm/radeon/atombios_dp.c | 44 ++++++++++++++++++++----------------
>>  1 file changed, 25 insertions(+), 19 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
>> index bc0119f..54e4f52 100644
>> --- a/drivers/gpu/drm/radeon/atombios_dp.c
>> +++ b/drivers/gpu/drm/radeon/atombios_dp.c
>> @@ -366,11 +366,11 @@ static void radeon_dp_probe_oui(struct radeon_connector *radeon_connector)
>>      if (!(dig_connector->dpcd[DP_DOWN_STREAM_PORT_COUNT] & DP_OUI_SUPPORT))
>>          return;
>>  -    if (drm_dp_dpcd_read(&radeon_connector->ddc_bus->aux, DP_SINK_OUI, buf, 3))
>> +    if (drm_dp_dpcd_read(&radeon_connector->ddc_bus->aux, DP_SINK_OUI, buf, 3) == 3)
>>          DRM_DEBUG_KMS("Sink OUI: %02hx%02hx%02hx\n",
>>                    buf[0], buf[1], buf[2]);
>>  -    if (drm_dp_dpcd_read(&radeon_connector->ddc_bus->aux, DP_BRANCH_OUI, buf, 3))
>> +    if (drm_dp_dpcd_read(&radeon_connector->ddc_bus->aux, DP_BRANCH_OUI, buf, 3) == 3)
>>          DRM_DEBUG_KMS("Branch OUI: %02hx%02hx%02hx\n",
>>                    buf[0], buf[1], buf[2]);
>>  }
>> @@ -419,21 +419,23 @@ int radeon_dp_get_panel_mode(struct drm_encoder *encoder,
>>        if (dp_bridge != ENCODER_OBJECT_ID_NONE) {
>>          /* DP bridge chips */
>> -        drm_dp_dpcd_readb(&radeon_connector->ddc_bus->aux,
>> -                  DP_EDP_CONFIGURATION_CAP, &tmp);
>> -        if (tmp & 1)
>> -            panel_mode = DP_PANEL_MODE_INTERNAL_DP2_MODE;
>> -        else if ((dp_bridge == ENCODER_OBJECT_ID_NUTMEG) ||
>> -             (dp_bridge == ENCODER_OBJECT_ID_TRAVIS))
>> -            panel_mode = DP_PANEL_MODE_INTERNAL_DP1_MODE;
>> -        else
>> -            panel_mode = DP_PANEL_MODE_EXTERNAL_DP_MODE;
>> +        if (drm_dp_dpcd_readb(&radeon_connector->ddc_bus->aux,
>> +                      DP_EDP_CONFIGURATION_CAP, &tmp) == 1) {
>> +            if (tmp & 1)
>> +                panel_mode = DP_PANEL_MODE_INTERNAL_DP2_MODE;
>> +            else if ((dp_bridge == ENCODER_OBJECT_ID_NUTMEG) ||
>> +                 (dp_bridge == ENCODER_OBJECT_ID_TRAVIS))
>> +                panel_mode = DP_PANEL_MODE_INTERNAL_DP1_MODE;
>> +            else
>> +                panel_mode = DP_PANEL_MODE_EXTERNAL_DP_MODE;
>> +        }
>>      } else if (connector->connector_type == DRM_MODE_CONNECTOR_eDP) {
>>          /* eDP */
>> -        drm_dp_dpcd_readb(&radeon_connector->ddc_bus->aux,
>> -                  DP_EDP_CONFIGURATION_CAP, &tmp);
>> -        if (tmp & 1)
>> -            panel_mode = DP_PANEL_MODE_INTERNAL_DP2_MODE;
>> +        if (drm_dp_dpcd_readb(&radeon_connector->ddc_bus->aux,
>> +                      DP_EDP_CONFIGURATION_CAP, &tmp) == 1) {
>> +            if (tmp & 1)
>> +                panel_mode = DP_PANEL_MODE_INTERNAL_DP2_MODE;
>> +        }
>>      }
>>        return panel_mode;
>> @@ -809,11 +811,15 @@ void radeon_dp_link_train(struct drm_encoder *encoder,
>>      else
>>          dp_info.enc_id |= ATOM_DP_CONFIG_LINK_A;
>>  -    drm_dp_dpcd_readb(&radeon_connector->ddc_bus->aux, DP_MAX_LANE_COUNT, &tmp);
>> -    if (ASIC_IS_DCE5(rdev) && (tmp & DP_TPS3_SUPPORTED))
>> -        dp_info.tp3_supported = true;
>> -    else
>> +    if (drm_dp_dpcd_readb(&radeon_connector->ddc_bus->aux, DP_MAX_LANE_COUNT, &tmp)
>> +        == 1) {
>> +        if (ASIC_IS_DCE5(rdev) && (tmp & DP_TPS3_SUPPORTED))
>> +            dp_info.tp3_supported = true;
>> +        else
>> +            dp_info.tp3_supported = false;
>> +    } else {
>>          dp_info.tp3_supported = false;
>> +    }
>>        memcpy(dp_info.dpcd, dig_connector->dpcd, DP_RECEIVER_CAP_SIZE);
>>      dp_info.rdev = rdev;
>