pcilmr: Add function for default margining results log

Lanes are rated according to the minimum/recommended values.
The minimum values are taken from PCIe Base Spec Rev 5.0 section 8.4.4.
30% UI recommended value for timing is taken from NVIDIA presentation
"PCIe 4.0 Mass Electrical Margins Data Collection".

Receiver lanes are called 'Weird' if all results of all receiver lanes
are equal to the spec minimum value.

Reviewed-by: Sergei Miroshnichenko <s.miroshnichenko@yadro.com>
Signed-off-by: Nikita Proshkin <n.proshkin@yadro.com>

2 files changed, 167 insertions, 0 deletions

diff --git a/lmr/lmr.h b/lmr/lmr.h
index c3a5039..d35b8ae 100644
--- a/lmr/lmr.h
+++ b/lmr/lmr.h
@@ -17,6 +17,10 @@
 
 #define MARGIN_STEP_MS 1000
 
+#define MARGIN_TIM_MIN       20
+#define MARGIN_TIM_RECOMMEND 30
+#define MARGIN_VOLT_MIN      50
+
 /* PCI Device wrapper for margining functions */
 struct margin_dev {
   struct pci_dev *dev;
@@ -205,4 +209,8 @@ void margin_log_receiver(struct margin_recv *recv);
 /* Margining in progress log */
 void margin_log_margining(struct margin_lanes_data arg);
 
+/* margin_results */
+
+void margin_results_print_brief(struct margin_results *results, u8 recvs_n);
+
 #endif
diff --git a/lmr/margin_results.c b/lmr/margin_results.c
new file mode 100644
index 0000000..5ee065d
--- /dev/null
+++ b/lmr/margin_results.c
@@ -0,0 +1,159 @@
+/*
+ *	The PCI Utilities -- Display/save margining results
+ *
+ *	Copyright (c) 2023 KNS Group LLC (YADRO)
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL v2+.
+ *
+ *	SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#include "lmr.h"
+
+enum lane_rating {
+  BAD = 0,
+  OKAY,
+  PERFECT,
+  WEIRD,
+  INIT,
+};
+
+static char *const grades[] = { "Bad", "Okay", "Perfect", "Weird" };
+static char *const sts_strings[] = { "NAK", "LIM", "THR" };
+static const double ui[] = { 62.5 / 100, 31.25 / 100 };
+
+static enum lane_rating
+rate_lane(double value, double min, double recommended, enum lane_rating cur_rate)
+{
+  enum lane_rating res = PERFECT;
+  if (value < recommended)
+    res = OKAY;
+  if (value < min)
+    res = BAD;
+  if (cur_rate == INIT)
+    return res;
+  if (res < cur_rate)
+    return res;
+  else
+    return cur_rate;
+}
+
+static bool
+check_recv_weird(struct margin_results *results, double tim_min, double volt_min)
+{
+  bool result = true;
+
+  struct margin_res_lane *lane;
+  for (int i = 0; i < results->lanes_n && result; i++)
+    {
+      lane = &(results->lanes[i]);
+      if (lane->steps[TIM_LEFT] * results->tim_coef != tim_min)
+        result = false;
+      if (results->params.ind_left_right_tim
+          && lane->steps[TIM_RIGHT] * results->tim_coef != tim_min)
+        result = false;
+      if (results->params.volt_support)
+        {
+          if (lane->steps[VOLT_UP] * results->volt_coef != volt_min)
+            result = false;
+          if (results->params.ind_up_down_volt
+              && lane->steps[VOLT_DOWN] * results->volt_coef != volt_min)
+            result = false;
+        }
+    }
+  return result;
+}
+
+void
+margin_results_print_brief(struct margin_results *results, u8 recvs_n)
+{
+  struct margin_res_lane *lane;
+  struct margin_results *res;
+  struct margin_params params;
+
+  enum lane_rating lane_rating;
+
+  u8 link_speed;
+
+  char *no_test_msgs[] = { "",
+                           "Margining Ready bit is Clear",
+                           "Error during caps reading",
+                           "Margining prerequisites are not satisfied (16/32 GT/s, D0)",
+                           "Invalid lanes specified with arguments",
+                           "Invalid receivers specified with arguments",
+                           "Couldn't disable ASPM" };
+
+  for (int i = 0; i < recvs_n; i++)
+    {
+      res = &(results[i]);
+      params = res->params;
+      link_speed = res->link_speed - 4;
+
+      if (res->test_status != MARGIN_TEST_OK)
+        {
+          if (res->test_status < MARGIN_TEST_PREREQS)
+            printf("Rx(%X) -", 10 + res->recvn - 1);
+          printf(" Couldn't run test (%s)\n\n", no_test_msgs[res->test_status]);
+          continue;
+        }
+
+      if (res->lane_reversal)
+        printf("Rx(%X) - Lane Reversal\n", 10 + res->recvn - 1);
+
+      if (check_recv_weird(res, MARGIN_TIM_MIN, MARGIN_VOLT_MIN))
+        lane_rating = WEIRD;
+      else
+        lane_rating = INIT;
+
+      for (u8 j = 0; j < res->lanes_n; j++)
+        {
+          lane = &(res->lanes[j]);
+          double left_ui = lane->steps[TIM_LEFT] * res->tim_coef;
+          double right_ui = lane->steps[TIM_RIGHT] * res->tim_coef;
+          double up_volt = lane->steps[VOLT_UP] * res->volt_coef;
+          double down_volt = lane->steps[VOLT_DOWN] * res->volt_coef;
+
+          if (lane_rating != WEIRD)
+            {
+              lane_rating = rate_lane(left_ui, MARGIN_TIM_MIN, MARGIN_TIM_RECOMMEND, INIT);
+              if (params.ind_left_right_tim)
+                lane_rating
+                  = rate_lane(right_ui, MARGIN_TIM_MIN, MARGIN_TIM_RECOMMEND, lane_rating);
+              if (params.volt_support)
+                {
+                  lane_rating = rate_lane(up_volt, MARGIN_VOLT_MIN, MARGIN_VOLT_MIN, lane_rating);
+                  if (params.ind_up_down_volt)
+                    lane_rating
+                      = rate_lane(down_volt, MARGIN_VOLT_MIN, MARGIN_VOLT_MIN, lane_rating);
+                }
+            }
+
+          printf("Rx(%X) Lane %2d - %s\t", 10 + res->recvn - 1, lane->lane, grades[lane_rating]);
+          if (params.ind_left_right_tim)
+            printf("L %4.1f%% UI - %5.2fps - %2dst %s, R %4.1f%% UI - %5.2fps - %2dst %s", left_ui,
+                   left_ui * ui[link_speed], lane->steps[TIM_LEFT],
+                   sts_strings[lane->statuses[TIM_LEFT]], right_ui, right_ui * ui[link_speed],
+                   lane->steps[TIM_RIGHT], sts_strings[lane->statuses[TIM_RIGHT]]);
+          else
+            printf("T %4.1f%% UI - %5.2fps - %2dst %s", left_ui, left_ui * ui[link_speed],
+                   lane->steps[TIM_LEFT], sts_strings[lane->statuses[TIM_LEFT]]);
+          if (params.volt_support)
+            {
+              if (params.ind_up_down_volt)
+                printf(", U %5.1f mV - %3dst %s, D %5.1f mV - %3dst %s", up_volt,
+                       lane->steps[VOLT_UP], sts_strings[lane->statuses[VOLT_UP]], down_volt,
+                       lane->steps[VOLT_DOWN], sts_strings[lane->statuses[VOLT_DOWN]]);
+              else
+                printf(", V %5.1f mV - %3dst %s", up_volt, lane->steps[VOLT_UP],
+                       sts_strings[lane->statuses[VOLT_UP]]);
+            }
+          printf("\n");
+        }
+      printf("\n");
+    }
+}