[PATCH] drm/i915: intel_dp_check_link_status should only return status of link

Manasi Navare
2016-07-01T22:35:57Z

Intel_dp_check_link_status() function reads the Link status registers
and returns a boolean to indicate link is good or bad.
If the link is bad, it is retrained outside the function based
on the return value.

Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
---
drivers/gpu/drm/i915/intel_dp.c | 41 ++++++++++++++++++++++++-----------------
1 file changed, 24 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 6d586b7..c795c9e 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3863,7 +3863,7 @@ go_again:
return -EINVAL;
}

-static void
+static bool
intel_dp_check_link_status(struct intel_dp *intel_dp)
{
struct intel_encoder *intel_encoder = &dp_to_dig_port(intel_dp)->base;
@@ -3873,26 +3873,25 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));

if (!intel_dp_get_link_status(intel_dp, link_status)) {
- DRM_ERROR("Failed to get link status\n");
- return;
+ DRM_DEBUG_KMS("Failed to get link status\n");
+ return false;
}

- if (!intel_encoder->base.crtc)
- return;
+ /* Check if the link is valid by reading the bits of Link status
+ * registers
+ */
+ if (!drm_dp_channel_eq_ok(link_status, intel_dp->lane_count) ||
+ !drm_dp_clock_recovery_ok(link_status, intel_dp->lane_count)) {
+ DRM_DEBUG_KMS("Channel EQ or CR not ok, need to retrain\n");
+ return false;
+ }

- if (!to_intel_crtc(intel_encoder->base.crtc)->active)
- return;
+ DRM_DEBUG_KMS("Link is good, no need to retrain\n");
+ return true;

- /* if link training is requested we should perform it always */
- if ((intel_dp->compliance_test_type == DP_TEST_LINK_TRAINING) ||
- (!drm_dp_channel_eq_ok(link_status, intel_dp->lane_count))) {
- DRM_DEBUG_KMS("%s: channel EQ not ok, retraining\n",
- intel_encoder->base.name);
- intel_dp_start_link_train(intel_dp);
- intel_dp_stop_link_train(intel_dp);
- }
}

+
/*
* According to DP spec
* 5.1.2:
@@ -3950,7 +3949,11 @@ intel_dp_short_pulse(struct intel_dp *intel_dp)
}

drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
- intel_dp_check_link_status(intel_dp);
+ if (!intel_dp_check_link_status(intel_dp) ||
+ intel_dp->compliance_test_type == DP_TEST_LINK_TRAINING) {
+ intel_dp_start_link_train(intel_dp);
+ intel_dp_stop_link_train(intel_dp);
+ }
drm_modeset_unlock(&dev->mode_config.connection_mutex);

return true;
@@ -4271,7 +4274,11 @@ intel_dp_long_pulse(struct intel_connector *intel_connector)
* link loss triggerring long pulse!!!!
*/
drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
- intel_dp_check_link_status(intel_dp);
+ if (!intel_dp_check_link_status(intel_dp) ||
+ intel_dp->compliance_test_type == DP_TEST_LINK_TRAINING) {
+ intel_dp_start_link_train(intel_dp);
+ intel_dp_stop_link_train(intel_dp);
+ }
drm_modeset_unlock(&dev->mode_config.connection_mutex);
goto out;
}
--
1.9.1