drm/debugfs: add an "edid_override" file per connector

Add a file to debugfs for each connector to allow the EDID to be
overridden.

v2: Copy ubuf before accessing it and reject invalid length data. (David
    Herrmann)
    Ensure override_edid is reset when a new EDID value is written.
    (David Herrmann)
    Fix the debugfs file permissions. (David Herrmann)

Signed-off-by: Thomas Wood <thomas.wood@intel.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 68 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c
index 8ab3f3e38643..13bd42923dd4 100644
--- a/drivers/gpu/drm/drm_debugfs.c
+++ b/drivers/gpu/drm/drm_debugfs.c
@@ -35,6 +35,7 @@
 #include <linux/slab.h>
 #include <linux/export.h>
 #include <drm/drmP.h>
+#include <drm/drm_edid.h>
 
 #if defined(CONFIG_DEBUG_FS)
 
@@ -304,6 +305,67 @@ static ssize_t connector_write(struct file *file, const char __user *ubuf,
         return len;
 }
 
+static int edid_show(struct seq_file *m, void *data)
+{
+        struct drm_connector *connector = m->private;
+        struct drm_property_blob *edid = connector->edid_blob_ptr;
+
+        if (connector->override_edid && edid)
+                seq_write(m, edid->data, edid->length);
+
+        return 0;
+}
+
+static int edid_open(struct inode *inode, struct file *file)
+{
+        struct drm_connector *dev = inode->i_private;
+
+        return single_open(file, edid_show, dev);
+}
+
+static ssize_t edid_write(struct file *file, const char __user *ubuf,
+                          size_t len, loff_t *offp)
+{
+        struct seq_file *m = file->private_data;
+        struct drm_connector *connector = m->private;
+        char *buf;
+        struct edid *edid;
+        int ret;
+
+        buf = memdup_user(ubuf, len);
+        if (IS_ERR(buf))
+                return PTR_ERR(buf);
+
+        edid = (struct edid *) buf;
+
+        if (len == 5 && !strncmp(buf, "reset", 5)) {
+                connector->override_edid = false;
+                ret = drm_mode_connector_update_edid_property(connector, NULL);
+        } else if (len < EDID_LENGTH ||
+                   EDID_LENGTH * (1 + edid->extensions) > len)
+                ret = -EINVAL;
+        else {
+                connector->override_edid = false;
+                ret = drm_mode_connector_update_edid_property(connector, edid);
+                if (!ret)
+                        connector->override_edid = true;
+        }
+
+        kfree(buf);
+
+        return (ret) ? ret : len;
+}
+
+static const struct file_operations drm_edid_fops = {
+        .owner = THIS_MODULE,
+        .open = edid_open,
+        .read = seq_read,
+        .llseek = seq_lseek,
+        .release = single_release,
+        .write = edid_write
+};
+
+
 static const struct file_operations drm_connector_fops = {
         .owner = THIS_MODULE,
         .open = connector_open,
@@ -333,6 +395,12 @@ int drm_debugfs_connector_add(struct drm_connector *connector)
         if (!ent)
                 goto error;
 
+        /* edid */
+        ent = debugfs_create_file("edid_override", S_IRUGO | S_IWUSR, root,
+                                  connector, &drm_edid_fops);
+        if (!ent)
+                goto error;
+
         return 0;
 
 error: