Implements basic link training functionality for Displayport automated
compliance
testing.
Signed-off-by: Todd Previte <tprev...@gmail.com>
---
drivers/gpu/drm/i915/intel_dp.c | 47 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 47 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 65830e9..e4b31ad 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3427,6 +3427,53 @@ static uint8_t
intel_dp_autotest_link_training(struct intel_dp *intel_dp)
{
uint8_t test_result = DP_TEST_NAK;
+ uint8_t rxdata[2];
+ uint8_t link_status[DP_LINK_STATUS_SIZE];
+ int bytes_ret = 0;
+ struct drm_connector *connector = &intel_dp->attached_connector->base;
+ struct intel_digital_port *intel_dig_port =
+ enc_to_dig_port(&intel_dp->attached_connector->encoder->base);
+
+ /* Read test parameters */
+ bytes_ret = drm_dp_dpcd_read(&intel_dp->aux, DP_TEST_LINK_RATE, rxdata,
2);
+
+ /* Set link rate directly */
+ intel_dp->link_bw = rxdata[0];
+ /* Preserve 7:5 when setting lane count */
+ intel_dp->lane_count &= 0xE0;
+ intel_dp->lane_count |= rxdata[1];
+
+ DRM_DEBUG_KMS("Displayport: Link training testing - %d lanes @ %02x
link rate\n",
+ intel_dp->lane_count, intel_dp->link_bw);
+
+ /* Train the link */
+ intel_dp->DP = intel_dig_port->saved_port_bits |
+ DDI_BUF_CTL_ENABLE |
+ DDI_BUF_EMP_400MV_0DB_HSW;
+ intel_dp->DP |= DDI_PORT_WIDTH(intel_dp->lane_count);
+
+ if (!intel_dp_start_link_train(intel_dp)) {
+ DRM_DEBUG_KMS("Displayport: intel_dp_start_link_train()
failed\n");
+ test_result = false;
+ }
+ if (!intel_dp_complete_link_train(intel_dp)) {
+ DRM_DEBUG_KMS("Displayport: intel_dp_complete_link_train()
failed\n");
+ test_result = false;
+ }
+ if (!intel_dp_stop_link_train(intel_dp)) {
+ DRM_DEBUG_KMS("Displayport: intel_dp_stop_link_train()
failed\n");
+ test_result = false;
+ }
+
+ /* Check link status for successful completion */
+ if (drm_dp_channel_eq_ok(link_status, intel_dp->lane_count))
+ test_result = true;
+
+ if (test_result == false) {
+ /* Clear link training here */
+ intel_dp_set_idle_link_train(intel_dp);
+ }
+
return test_result;
}
--
1.9.1
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