[PATCH 1/5] drm/i915: Add support for DP link training compliance

Manasi Navare
2016-11-22T21:39:22Z

This patch adds support to handle automated DP compliance
link training test requests. This patch has been tested with
Unigraf DPR-120 DP Compliance device for testing Link
Training Compliance.
After we get a short pulse Compliance test request, test
request values are read and hotplug uevent is sent in order
to trigger another modeset during which the pipe is configured
and link is retrained and enabled for link parameters requested
by the test.

Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
---
drivers/gpu/drm/i915/intel_dp.c | 73 ++++++++++++++++++++++++++++++++++++----
drivers/gpu/drm/i915/intel_drv.h | 2 ++
2 files changed, 69 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 90283ed..69944d1 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -288,6 +288,21 @@ static int intel_dp_common_rates(struct intel_dp *intel_dp,
common_rates);
}

+static int intel_dp_link_rate_index(struct intel_dp *intel_dp,
+ int *common_rates, int link_rate)
+{
+ int common_len;
+ int index;
+
+ common_len = intel_dp_common_rates(intel_dp, common_rates);
+ for (index = 0; index < common_len; index++) {
+ if (link_rate == common_rates[common_len - index - 1])
+ return common_len - index - 1;
+ }
+
+ return -1;
+}
+
static enum drm_mode_status
intel_dp_mode_valid(struct drm_connector *connector,
struct drm_display_mode *mode)
@@ -1554,6 +1569,7 @@ static int intel_dp_compute_bpp(struct intel_dp *intel_dp,
/* Conveniently, the link BW constants become indices with a shift...*/
int min_clock = 0;
int max_clock;
+ int link_rate_index;
int bpp, mode_rate;
int link_avail, link_clock;
int common_rates[DP_MAX_SUPPORTED_RATES] = {};
@@ -1595,6 +1611,16 @@ static int intel_dp_compute_bpp(struct intel_dp *intel_dp,
if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
return false;

+ /* Use values requested by Compliance Test Request */
+ if (intel_dp->compliance_test_type == DP_TEST_LINK_TRAINING) {
+ link_rate_index = intel_dp_link_rate_index(intel_dp,
+ common_rates,
+ drm_dp_bw_code_to_link_rate(intel_dp->compliance_test_link_rate));
+ if (link_rate_index >= 0)
+ min_clock = max_clock = link_rate_index;
+ min_lane_count = max_lane_count = intel_dp->compliance_test_lane_count;
+ }
+
DRM_DEBUG_KMS("DP link computation with max lane count %i "
"max bw %d pixel clock %iKHz\n",
max_lane_count, common_rates[max_clock],
@@ -1642,6 +1668,7 @@ static int intel_dp_compute_bpp(struct intel_dp *intel_dp,
}
}
}
+
}

return false;
@@ -3804,6 +3831,29 @@ int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc)
static uint8_t intel_dp_autotest_link_training(struct intel_dp *intel_dp)
{
uint8_t test_result = DP_TEST_ACK;
+ int status = 0;
+ /* (DP CTS 1.2)
+ * 4.3.1.11
+ */
+ /* Read the TEST_LANE_COUNT and TEST_LINK_RTAE fields (DP CTS 3.1.4) */
+ status = drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_LANE_COUNT,
+ &intel_dp->compliance_test_lane_count);
+
+ if (status <= 0) {
+ DRM_DEBUG_KMS("Could not read test lane count from "
+ "reference sink\n");
+ return 0;
+ }
+ intel_dp->compliance_test_lane_count &= DP_MAX_LANE_COUNT_MASK;
+
+ status = drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_LINK_RATE,
+ &intel_dp->compliance_test_link_rate);
+ if (status <= 0) {
+ DRM_DEBUG_KMS("Could not read test link rate from "
+ "refernce sink\n");
+ return 0;
+ }
+
return test_result;
}

@@ -3908,7 +3958,8 @@ static void intel_dp_handle_test_request(struct intel_dp *intel_dp)
DP_TEST_RESPONSE,
&response, 1);
if (status <= 0)
- DRM_DEBUG_KMS("Could not write test response to sink\n");
+ DRM_DEBUG_KMS("Could not write test response "
+ "to sink\n");
}

static int
@@ -4018,9 +4069,8 @@ static void intel_dp_handle_test_request(struct intel_dp *intel_dp)
if (WARN_ON_ONCE(!intel_dp->lane_count))
return;

- /* 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))) {
+ /* Retrain if Channel EQ or CR not ok */
+ if ((!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);

@@ -4045,6 +4095,7 @@ static void intel_dp_handle_test_request(struct intel_dp *intel_dp)
intel_dp_short_pulse(struct intel_dp *intel_dp)
{
struct drm_device *dev = intel_dp_to_dev(intel_dp);
+ struct intel_encoder *intel_encoder = &dp_to_dig_port(intel_dp)->base;
u8 sink_irq_vector = 0;
u8 old_sink_count = intel_dp->sink_count;
bool ret;
@@ -4056,6 +4107,8 @@ static void intel_dp_handle_test_request(struct intel_dp *intel_dp)
intel_dp->compliance_test_active = 0;
intel_dp->compliance_test_type = 0;
intel_dp->compliance_test_data = 0;
+ intel_dp->compliance_test_lane_count = 0;
+ intel_dp->compliance_test_link_rate = 0;

/*
* Now read the DPCD to see if it's actually running
@@ -4079,8 +4132,9 @@ static void intel_dp_handle_test_request(struct intel_dp *intel_dp)
DP_DEVICE_SERVICE_IRQ_VECTOR,
sink_irq_vector);

- if (sink_irq_vector & DP_AUTOMATED_TEST_REQUEST)
- DRM_DEBUG_DRIVER("Test request in short pulse not handled\n");
+ if (sink_irq_vector & DP_AUTOMATED_TEST_REQUEST) {
+ intel_dp_handle_test_request(intel_dp);
+ }
if (sink_irq_vector & (DP_CP_IRQ | DP_SINK_SPECIFIC_IRQ))
DRM_DEBUG_DRIVER("CP or sink specific irq unhandled\n");
}
@@ -4088,6 +4142,11 @@ static void intel_dp_handle_test_request(struct intel_dp *intel_dp)
drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
intel_dp_check_link_status(intel_dp);
drm_modeset_unlock(&dev->mode_config.connection_mutex);
+ if ((intel_dp->compliance_test_type == DP_TEST_LINK_TRAINING)) {
+ DRM_DEBUG_KMS("Link Training Compliance Test requested\n");
+ /* Send a Hotplug Uevent to userspace to start modeset */
+ drm_kms_helper_hotplug_event(intel_encoder->base.dev);
+ }

return true;
}
@@ -4375,6 +4434,8 @@ static bool intel_digital_port_connected(struct drm_i915_private *dev_priv,
intel_dp->compliance_test_active = 0;
intel_dp->compliance_test_type = 0;
intel_dp->compliance_test_data = 0;
+ intel_dp->compliance_test_lane_count = 0;
+ intel_dp->compliance_test_link_rate = 0;

if (intel_dp->is_mst) {
DRM_DEBUG_KMS("MST device may have disappeared %d vs %d\n",
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index cd132c2..1e88288 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -958,6 +958,8 @@ struct intel_dp {
unsigned long compliance_test_type;
unsigned long compliance_test_data;
bool compliance_test_active;
+ u8 compliance_test_lane_count;
+ u8 compliance_test_link_rate;
};

struct intel_lspcon {
--
1.9.1