[Intel-gfx] [PATCH] drm/i915: Add bigjoiner force enable option to debugfs

[Stanislav Lisovskiy]

For validation purposes, it might be useful to be able to
force Bigjoiner mode, even if current dotclock/resolution
do not require that.
Lets add such to option to debugfs.

v2: - Apparently intel_dp_need_bigjoiner can't be used, when
      debugfs entry is created so lets just check manually
      the DISPLAY_VER.

v3: - Switch to intel_connector from drm_connector(Jani Nikula)
    - Remove redundant modeset lock(Jani Nikula)
    - Use kstrtobool_from_user for boolean value(Jani Nikula)

v4: - Apply the changes to proper function(Jani Nikula)

Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
---
 .../drm/i915/display/intel_display_debugfs.c  | 66 +++++++++++++++++++
 .../drm/i915/display/intel_display_types.h    |  2 +
 drivers/gpu/drm/i915/display/intel_dp.c       |  6 +-
 3 files changed, 73 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
index fbe75d47a165..9b810c6f96ea 100644
--- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
+++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
@@ -1398,6 +1398,30 @@ out:	drm_modeset_unlock(&dev->mode_config.connection_mutex);
 	return ret;
 }
 
+static int i915_bigjoiner_enable_show(struct seq_file *m, void *data)
+{
+	struct intel_connector *connector = to_intel_connector(m->private);
+	struct drm_crtc *crtc;
+	struct intel_encoder *encoder = intel_attached_encoder(connector);
+	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
+	int ret = 0;
+
+	if (!encoder)
+		return -ENODEV;
+
+	crtc = connector->base.state->crtc;
+	if (connector->base.status != connector_status_connected || !crtc) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	seq_printf(m, "Bigjoiner enable: %d\n", intel_dp->force_bigjoiner_enable);
+
+out:
+
+	return ret;
+}
+
 static ssize_t i915_dsc_output_format_write(struct file *file,
 					    const char __user *ubuf,
 					    size_t len, loff_t *offp)
@@ -1419,12 +1443,39 @@ static ssize_t i915_dsc_output_format_write(struct file *file,
 	return len;
 }
 
+static ssize_t i915_bigjoiner_enable_fops_write(struct file *file,
+						const char __user *ubuf,
+						size_t len, loff_t *offp)
+{
+	struct seq_file *m = file->private_data;
+	struct intel_connector *connector = m->private;
+	struct intel_encoder *encoder = intel_attached_encoder(connector);
+	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
+	bool bigjoiner_en = 0;
+	int ret;
+
+	ret = kstrtobool_from_user(ubuf, len, &bigjoiner_en);
+	if (ret < 0)
+		return ret;
+
+	intel_dp->force_bigjoiner_enable = bigjoiner_en;
+	*offp += len;
+
+	return len;
+}
+
 static int i915_dsc_output_format_open(struct inode *inode,
 				       struct file *file)
 {
 	return single_open(file, i915_dsc_output_format_show, inode->i_private);
 }
 
+static int i915_bigjoiner_enable_open(struct inode *inode,
+				      struct file *file)
+{
+	return single_open(file, i915_bigjoiner_enable_show, inode->i_private);
+}
+
 static const struct file_operations i915_dsc_output_format_fops = {
 	.owner = THIS_MODULE,
 	.open = i915_dsc_output_format_open,
@@ -1434,6 +1485,15 @@ static const struct file_operations i915_dsc_output_format_fops = {
 	.write = i915_dsc_output_format_write
 };
 
+static const struct file_operations i915_bigjoiner_enable_fops = {
+	.owner = THIS_MODULE,
+	.open = i915_bigjoiner_enable_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+	.write = i915_bigjoiner_enable_fops_write
+};
+
 /*
  * Returns the Current CRTC's bpc.
  * Example usage: cat /sys/kernel/debug/dri/0/crtc-0/i915_current_bpc
@@ -1513,6 +1573,12 @@ void intel_connector_debugfs_add(struct intel_connector *intel_connector)
 				    connector, &i915_dsc_output_format_fops);
 	}
 
+	if (DISPLAY_VER(dev_priv) >= 11 &&
+	    intel_connector->base.connector_type == DRM_MODE_CONNECTOR_DisplayPort) {
+		debugfs_create_file("i915_bigjoiner_force_enable", 0644, root,
+				    &intel_connector->base, &i915_bigjoiner_enable_fops);
+	}
+
 	if (connector->connector_type == DRM_MODE_CONNECTOR_DSI ||
 	    connector->connector_type == DRM_MODE_CONNECTOR_eDP ||
 	    connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 8d8b2f8d37a9..e0de6eeaf59e 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1753,6 +1753,8 @@ struct intel_dp {
 	bool is_mst;
 	int active_mst_links;
 
+	bool force_bigjoiner_enable;
+
 	/* connector directly attached - won't be use for modeset in mst world */
 	struct intel_connector *attached_connector;
 
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 4f6835a7578e..6a9148232a9c 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -1153,7 +1153,11 @@ bool intel_dp_need_bigjoiner(struct intel_dp *intel_dp,
 	if (!intel_dp_can_bigjoiner(intel_dp))
 		return false;
 
-	return clock > i915->max_dotclk_freq || hdisplay > 5120;
+	if (intel_dp->force_bigjoiner_enable)
+		drm_dbg_kms(&i915->drm, "Forcing bigjoiner mode\n");
+
+	return clock > i915->max_dotclk_freq || hdisplay > 5120 ||
+	       intel_dp->force_bigjoiner_enable;
 }
 
 static enum drm_mode_status
-- 
2.37.3