drm/i915/display: Modify debugfs for joiner to force n pipes

At the moment, the debugfs for joiner allows only to force enable/disable
pipe joiner for 2 pipes. Modify it to force join 'n' number of pipes,
where n is a valid pipe joiner configuration.
This will help in case of ultra joiner where 4 pipes are joined.

v2:
-Fix commit message to state that only valid joiner config can be
forced. (Suraj)
-Rename the identifiers to have INTEL_BIG/NONE_JOINER_PIPES. (Suraj)
v3:
-Avoid enum for joiner pipe counts, use bare numbers for better
readability. (Ville)
-Remove redundant prints from debugfs. (Ville)
v4: Return -EINVAL if joiner forced to an invalid value.
v5: Remove extra debug message. (Ville)
v6: Minor fix in switch case. (Ville)

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240926134322.3728021-4-ankit.k.nautiyal@intel.com

1 files changed, 55 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
index c38023b43682..ae3715f0f1d8 100644
--- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
+++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
@@ -1316,6 +1316,59 @@ static int intel_crtc_pipe_show(struct seq_file *m, void *unused)
 }
 DEFINE_SHOW_ATTRIBUTE(intel_crtc_pipe);
 
+static int i915_joiner_show(struct seq_file *m, void *data)
+{
+	struct intel_connector *connector = m->private;
+
+	seq_printf(m, "%d\n", connector->force_joined_pipes);
+
+	return 0;
+}
+
+static ssize_t i915_joiner_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;
+	int force_joined_pipes = 0;
+	int ret;
+
+	if (len == 0)
+		return 0;
+
+	ret = kstrtoint_from_user(ubuf, len, 0, &force_joined_pipes);
+	if (ret < 0)
+		return ret;
+
+	switch (force_joined_pipes) {
+	case 0:
+	case 2:
+		connector->force_joined_pipes = force_joined_pipes;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	*offp += len;
+
+	return len;
+}
+
+static int i915_joiner_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, i915_joiner_show, inode->i_private);
+}
+
+static const struct file_operations i915_joiner_fops = {
+	.owner = THIS_MODULE,
+	.open = i915_joiner_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+	.write = i915_joiner_write
+};
+
 /**
  * intel_connector_debugfs_add - add i915 specific connector debugfs files
  * @connector: pointer to a registered intel_connector
@@ -1365,8 +1418,8 @@ void intel_connector_debugfs_add(struct intel_connector *connector)
 	if ((connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
 	     connector_type == DRM_MODE_CONNECTOR_eDP) &&
 	    intel_dp_has_joiner(intel_attached_dp(connector))) {
-		debugfs_create_bool("i915_bigjoiner_force_enable", 0644, root,
-				    &connector->force_bigjoiner_enable);
+		debugfs_create_file("i915_joiner_force_enable", 0644, root,
+				    connector, &i915_joiner_fops);
 	}
 
 	if (connector_type == DRM_MODE_CONNECTOR_DSI ||