[PATCH RFC 11/13] drm/connector: hdmi: Create Infoframe DebugFS entries

From: Maxime Ripard <mripard@kernel.org>
To: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>,
	Emma Anholt <emma@anholt.net>
Cc: Hans Verkuil <hverkuil@xs4all.nl>,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	Maxime Ripard <mripard@kernel.org>
Subject: [PATCH RFC 11/13] drm/connector: hdmi: Create Infoframe DebugFS entries
Date: Mon, 14 Aug 2023 15:56:23 +0200	[thread overview]
Message-ID: <20230814-kms-hdmi-connector-state-v1-11-048054df3654@kernel.org> (raw)
In-Reply-To: <20230814-kms-hdmi-connector-state-v1-0-048054df3654@kernel.org>

There has been some discussions recently about the infoframes sent by
drivers and if they were properly generated.

In parallel, there's been some interest in creating an infoframe-decode
tool similar to edid-decode.

Both would be much easier if we were to expose the infoframes programmed
in the hardware. It won't be perfect since we have no guarantee that
it's actually what goes through the wire, but it's the best we can do.

Signed-off-by: Maxime Ripard <mripard@kernel.org>
---
 drivers/gpu/drm/drm_hdmi_connector.c | 124 +++++++++++++++++++++++++++++++++++
 include/drm/drm_connector.h          |   4 ++
 2 files changed, 128 insertions(+)

diff --git a/drivers/gpu/drm/drm_hdmi_connector.c b/drivers/gpu/drm/drm_hdmi_connector.c
index 46cafb17def7..dcc45b1080f9 100644
--- a/drivers/gpu/drm/drm_hdmi_connector.c
+++ b/drivers/gpu/drm/drm_hdmi_connector.c
@@ -907,6 +907,130 @@ void drm_atomic_helper_hdmi_connector_print_state(struct drm_printer *p,
 }
 EXPORT_SYMBOL(drm_atomic_helper_hdmi_connector_print_state);
 
+struct debugfs_wrapper {
+	struct drm_hdmi_connector *hdmi_connector;
+	union hdmi_infoframe *frame;
+};
+
+static ssize_t
+infoframe_read(struct file *filp, char __user *ubuf, size_t count, loff_t *ppos)
+{
+	const struct debugfs_wrapper *wrapper = filp->private_data;
+	struct drm_hdmi_connector *hdmi_connector = wrapper->hdmi_connector;
+	union hdmi_infoframe *frame = wrapper->frame;
+	u8 buf[HDMI_MAX_INFOFRAME_SIZE];
+	ssize_t len;
+
+	len = hdmi_infoframe_pack(frame, buf, sizeof(buf));
+	if (len < 0)
+		return len;
+
+	mutex_lock(&hdmi_connector->infoframes.lock);
+	len = simple_read_from_buffer(ubuf, count, ppos, buf, len);
+	mutex_unlock(&hdmi_connector->infoframes.lock);
+
+	return len;
+}
+
+static const struct file_operations infoframe_fops = {
+	.owner   = THIS_MODULE,
+	.open    = simple_open,
+	.read    = infoframe_read,
+};
+
+static int create_debugfs_infoframe_file(struct drm_hdmi_connector *hdmi_connector,
+					 struct dentry *parent,
+					 const char *filename,
+					 union hdmi_infoframe *frame)
+{
+	struct drm_device *dev = hdmi_connector->base.dev;
+	struct debugfs_wrapper *wrapper;
+	struct dentry *file;
+
+	wrapper = drmm_kzalloc(dev, sizeof(*wrapper), GFP_KERNEL);
+	if (!wrapper)
+		return -ENOMEM;
+
+	wrapper->hdmi_connector = hdmi_connector;
+	wrapper->frame = frame;
+
+	file = debugfs_create_file(filename, 0400, parent, wrapper, &infoframe_fops);
+	if (IS_ERR(file))
+		return PTR_ERR(file);
+
+	return 0;
+}
+
+#define CREATE_INFOFRAME_FILE(c, p, i)		\
+	create_debugfs_infoframe_file(c, p, #i, (union hdmi_infoframe *)&(c)->infoframes.i)
+
+static int create_debugfs_infoframe_files(struct drm_hdmi_connector *hdmi_connector,
+					  struct dentry *parent)
+{
+	int ret;
+
+	ret = CREATE_INFOFRAME_FILE(hdmi_connector, parent, audio);
+	if (ret)
+		return ret;
+
+	ret = CREATE_INFOFRAME_FILE(hdmi_connector, parent, avi);
+	if (ret)
+		return ret;
+
+	ret = CREATE_INFOFRAME_FILE(hdmi_connector, parent, drm);
+	if (ret)
+		return ret;
+
+	ret = CREATE_INFOFRAME_FILE(hdmi_connector, parent, spd);
+	if (ret)
+		return ret;
+
+	ret = CREATE_INFOFRAME_FILE(hdmi_connector, parent, vendor);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+#undef CREATE_INFOFRAME_FILE
+
+static void remove_debugfs_dir(struct drm_device *dev, void *data)
+{
+	struct dentry *dir = data;
+
+	debugfs_remove_recursive(dir);
+}
+
+/**
+ * drm_helper_hdmi_connector_debugfs_init - DebugFS init for HDMI connectors
+ * @connector: Parent Connector
+ * @dentry: DebugFS root dentry
+ *
+ * Provides a default implementation for
+ * @drm_connector_helper_funcs.debugfs_init that will create all the
+ * files relevant for a @drm_hdmi_connector.
+ */
+void drm_helper_hdmi_connector_debugfs_init(struct drm_connector *connector,
+					    struct dentry *root)
+{
+	struct drm_hdmi_connector *hdmi_connector =
+		connector_to_hdmi_connector(connector);
+	struct drm_device *dev = hdmi_connector->base.dev;
+	struct dentry *dir;
+	int ret;
+
+	dir = debugfs_create_dir("infoframes", root);
+	if (IS_ERR(dir))
+		return;
+
+	ret = drmm_add_action_or_reset(dev, remove_debugfs_dir, dir);
+	if (ret)
+		return;
+
+	create_debugfs_infoframe_files(hdmi_connector, dir);
+}
+EXPORT_SYMBOL(drm_helper_hdmi_connector_debugfs_init);
+
 /**
  * drmm_hdmi_connector_init - Init a preallocated HDMI connector
  * @dev: DRM device
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 21da6f428101..e5faaeb35a9d 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -2294,6 +2294,10 @@ int drmm_hdmi_connector_init(struct drm_device *dev,
 			     struct i2c_adapter *ddc,
 			     unsigned int max_bpc);
 
+void drm_helper_hdmi_connector_debugfs_init(struct drm_connector *connector,
+					    struct dentry *root);
+
+
 /**
  * struct drm_tile_group - Tile group metadata
  * @refcount: reference count

-- 
2.41.0

