drm/amd/display: Add connector HPD trigger debugfs entry

[why]
Need a tool to retrigger a virtual hotplug for testing purposes with
force redetection in both DC and DM.

[how]
Emulate handle_hpd_irq for connector as if usermode would trigger
a hotplug. Perform DC link discovery, DM connector update, and
DM force atomic commit.

In order to trigger HPD on the connector user needs to echo 1 into
"trigger_hotplug" debugfs entry on its respective connector.

Signed-off-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Mikita Lipski <mikita.lipski@amd.com>
Reviewed-by: Mikita Lipski <Mikita.Lipski@amd.com>
Acked-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
index e097a60..94fcb08 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
@@ -1049,6 +1049,81 @@ static int dp_dsc_fec_support_show(struct seq_file *m, void *data)
        return ret;
 }
 
+/* function: Trigger virtual HPD redetection on connector
+ *
+ * This function will perform link rediscovery, link disable
+ * and enable, and dm connector state update.
+ *
+ * Retrigger HPD on an existing connector by echoing 1 into
+ * its respectful "trigger_hotplug" debugfs entry:
+ *
+ *     echo 1 > /sys/kernel/debug/dri/0/DP-X/trigger_hotplug
+ *
+ */
+static ssize_t dp_trigger_hotplug(struct file *f, const char __user *buf,
+                                                       size_t size, loff_t *pos)
+{
+       struct amdgpu_dm_connector *aconnector = file_inode(f)->i_private;
+       struct drm_connector *connector = &aconnector->base;
+       struct drm_device *dev = connector->dev;
+       enum dc_connection_type new_connection_type = dc_connection_none;
+       char *wr_buf = NULL;
+       uint32_t wr_buf_size = 42;
+       int max_param_num = 1;
+       long param[1] = {0};
+       uint8_t param_nums = 0;
+
+       if (!aconnector || !aconnector->dc_link)
+               return -EINVAL;
+
+       if (size == 0)
+               return -EINVAL;
+
+       wr_buf = kcalloc(wr_buf_size, sizeof(char), GFP_KERNEL);
+
+       if (!wr_buf) {
+               DRM_DEBUG_DRIVER("no memory to allocate write buffer\n");
+               return -ENOSPC;
+       }
+
+       if (parse_write_buffer_into_params(wr_buf, wr_buf_size,
+                                               (long *)param, buf,
+                                               max_param_num,
+                                               &param_nums))
+               return -EINVAL;
+
+       if (param_nums <= 0) {
+               DRM_DEBUG_DRIVER("user data not be read\n");
+               kfree(wr_buf);
+               return -EINVAL;
+       }
+
+       if (param[0] == 1) {
+               mutex_lock(&aconnector->hpd_lock);
+
+               if (!dc_link_detect_sink(aconnector->dc_link, &new_connection_type) &&
+                       new_connection_type != dc_connection_none)
+                       goto unlock;
+
+               if (!dc_link_detect(aconnector->dc_link, DETECT_REASON_HPD))
+                       goto unlock;
+
+               amdgpu_dm_update_connector_after_detect(aconnector);
+
+               drm_modeset_lock_all(dev);
+               dm_restore_drm_connector_state(dev, connector);
+               drm_modeset_unlock_all(dev);
+
+               drm_kms_helper_hotplug_event(dev);
+
+unlock:
+               mutex_unlock(&aconnector->hpd_lock);
+       }
+
+       kfree(wr_buf);
+       return size;
+}
+
 /* function: read DSC status on the connector
  *
  * The read function: dp_dsc_clock_en_read
@@ -1967,6 +2042,12 @@ static const struct file_operations dp_dsc_slice_bpg_offset_debugfs_fops = {
        .llseek = default_llseek
 };
 
+static const struct file_operations dp_trigger_hotplug_debugfs_fops = {
+       .owner = THIS_MODULE,
+       .write = dp_trigger_hotplug,
+       .llseek = default_llseek
+};
+
 static const struct file_operations dp_link_settings_debugfs_fops = {
        .owner = THIS_MODULE,
        .read = dp_link_settings_read,