drm/i915: Add debugfs entry to read/write next_seqno

This is needed for testing seqno wrapping. Be careful to not bump next_seqno
more than 0x7FFFFFFF at a time (between some handled requests) as
i915_seqno_passed() can't handle bigger difference in between.

v2: Address review comments from Chris Wilson.

Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
[danvet: Squash in fixup to properly remove the debugfs file on driver
unload again.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index ce60506b574bbbcda36830def1f93f0823499b94..602058fb5e25a5d25001bd279292e4efd0398d39 100644 (file)
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -843,6 +843,86 @@ static const struct file_operations i915_error_state_fops = {
        .release = i915_error_state_release,
 };
 
+static ssize_t
+i915_next_seqno_read(struct file *filp,
+                char __user *ubuf,
+                size_t max,
+                loff_t *ppos)
+{
+       struct drm_device *dev = filp->private_data;
+       drm_i915_private_t *dev_priv = dev->dev_private;
+       char buf[80];
+       int len;
+       int ret;
+
+       ret = mutex_lock_interruptible(&dev->struct_mutex);
+       if (ret)
+               return ret;
+
+       len = snprintf(buf, sizeof(buf),
+                      "next_seqno :  0x%x\n",
+                      dev_priv->next_seqno);
+
+       mutex_unlock(&dev->struct_mutex);
+
+       if (len > sizeof(buf))
+               len = sizeof(buf);
+
+       return simple_read_from_buffer(ubuf, max, ppos, buf, len);
+}
+
+static ssize_t
+i915_next_seqno_write(struct file *filp,
+                     const char __user *ubuf,
+                     size_t cnt,
+                     loff_t *ppos)
+{
+       struct drm_device *dev = filp->private_data;
+       drm_i915_private_t *dev_priv = dev->dev_private;
+       char buf[20];
+       u32 val = 1;
+       int ret;
+
+       if (cnt > 0) {
+               if (cnt > sizeof(buf) - 1)
+                       return -EINVAL;
+
+               if (copy_from_user(buf, ubuf, cnt))
+                       return -EFAULT;
+               buf[cnt] = 0;
+
+               ret = kstrtouint(buf, 0, &val);
+               if (ret < 0)
+                       return ret;
+       }
+
+       if (val == 0)
+               return -EINVAL;
+
+       ret = mutex_lock_interruptible(&dev->struct_mutex);
+       if (ret)
+               return ret;
+
+       if (i915_seqno_passed(val, dev_priv->next_seqno)) {
+               dev_priv->next_seqno = val;
+               DRM_DEBUG_DRIVER("Advancing seqno to %u\n", val);
+       } else {
+               ret = -EINVAL;
+       }
+
+       mutex_unlock(&dev->struct_mutex);
+
+       return ret ?: cnt;
+}
+
+static const struct file_operations i915_next_seqno_fops = {
+       .owner = THIS_MODULE,
+       .open = simple_open,
+       .read = i915_next_seqno_read,
+       .write = i915_next_seqno_write,
+       .llseek = default_llseek,
+};
+
 static int i915_rstdby_delays(struct seq_file *m, void *unused)
 {
        struct drm_info_node *node = (struct drm_info_node *) m->private;
@@ -2107,6 +2187,12 @@ int i915_debugfs_init(struct drm_minor *minor)
        if (ret)
                return ret;
 
+       ret = i915_debugfs_create(minor->debugfs_root, minor,
+                                "i915_next_seqno",
+                                &i915_next_seqno_fops);
+       if (ret)
+               return ret;
+
        return drm_debugfs_create_files(i915_debugfs_list,
                                        I915_DEBUGFS_ENTRIES,
                                        minor->debugfs_root, minor);
@@ -2130,6 +2216,8 @@ void i915_debugfs_cleanup(struct drm_minor *minor)
                                 1, minor);
        drm_debugfs_remove_files((struct drm_info_list *) &i915_error_state_fops,
                                 1, minor);
+       drm_debugfs_remove_files((struct drm_info_list *) &i915_next_seqno_fops,
+                                1, minor);
 }
 
 #endif /* CONFIG_DEBUG_FS */