drm/amd/display: Fix debugfs link_settings entry

1. Catch invalid link_rate and link_count settings
2. Call dc interface to overwrite preferred link settings, and wait
until next stream update to apply the new settings.
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Fangzhi Zuo <Jerry.Zuo@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Solomon Chiu <solomon.chiu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c

@@ -149,7 +149,7 @@ static int parse_write_buffer_into_params(char *wr_buf, uint32_t wr_buf_size,
  *
  * --- to get dp configuration
  *
- * cat link_settings
+ * cat /sys/kernel/debug/dri/0/DP-x/link_settings
  *
  * It will list current, verified, reported, preferred dp configuration.
  * current -- for current video mode
@@ -162,7 +162,7 @@ static int parse_write_buffer_into_params(char *wr_buf, uint32_t wr_buf_size,
  * echo <lane_count>  <link_rate> > link_settings
  *
  * for example, to force to  2 lane, 2.7GHz,
- * echo 4 0xa > link_settings
+ * echo 4 0xa > /sys/kernel/debug/dri/0/DP-x/link_settings
  *
  * spread_spectrum could not be changed dynamically.
  *
@@ -170,7 +170,7 @@ static int parse_write_buffer_into_params(char *wr_buf, uint32_t wr_buf_size,
  * done. please check link settings after force operation to see if HW get
  * programming.
  *
- * cat link_settings
+ * cat /sys/kernel/debug/dri/0/DP-x/link_settings
  *
  * check current and preferred settings.
  *
@@ -254,7 +254,7 @@ static ssize_t dp_link_settings_write(struct file *f, const char __user *buf,
 	int max_param_num = 2;
 	uint8_t param_nums = 0;
 	long param[2];
-	bool valid_input = false;
+	bool valid_input = true;
 
 	if (size == 0)
 		return -EINVAL;
@@ -281,9 +281,9 @@ static ssize_t dp_link_settings_write(struct file *f, const char __user *buf,
 	case LANE_COUNT_ONE:
 	case LANE_COUNT_TWO:
 	case LANE_COUNT_FOUR:
-		valid_input = true;
 		break;
 	default:
+		valid_input = false;
 		break;
 	}
 
@@ -293,9 +293,9 @@ static ssize_t dp_link_settings_write(struct file *f, const char __user *buf,
 	case LINK_RATE_RBR2:
 	case LINK_RATE_HIGH2:
 	case LINK_RATE_HIGH3:
-		valid_input = true;
 		break;
 	default:
+		valid_input = false;
 		break;
 	}
 
@@ -309,10 +309,11 @@ static ssize_t dp_link_settings_write(struct file *f, const char __user *buf,
 	 * spread spectrum will not be changed
 	 */
 	prefer_link_settings.link_spread = link->cur_link_settings.link_spread;
+	prefer_link_settings.use_link_rate_set = false;
 	prefer_link_settings.lane_count = param[0];
 	prefer_link_settings.link_rate = param[1];
 
-	dc_link_set_preferred_link_settings(dc, &prefer_link_settings, link);
+	dc_link_set_preferred_training_settings(dc, &prefer_link_settings, NULL, link, true);
 
 	kfree(wr_buf);
 	return size;