These helpers keep track of fbdev users and drm_driver.last_close will
only restore fbdev when actually in use. Additionally the display is
turned off when the last user is closing. fbcon is a user in this context.
If struct fb_ops is defined in a library, fb_open() takes a ref on the
library (fb_ops.owner) instead of the driver module. Fix that by ensuring
that the driver module is pinned.
The functions are not added to the DRM_FB_HELPER_DEFAULT_OPS() macro,
because some of its users do set fb_open/release themselves.
Signed-off-by: Noralf Trønnes <nor...@tronnes.org>
---
drivers/gpu/drm/drm_fb_helper.c | 54 ++++++++++++++++++++++++++++++++++++++++-
include/drm/drm_fb_helper.h | 29 ++++++++++++++++++++++
2 files changed, 82 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 98e5bc92c9f2..b1124c08b1ed 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -177,7 +177,7 @@ int drm_fb_helper_restore_fbdev_mode_unlocked(struct
drm_fb_helper *fb_helper)
if (!drm_fbdev_emulation || !fb_helper)
return -ENODEV;
- if (READ_ONCE(fb_helper->deferred_setup))
+ if (READ_ONCE(fb_helper->deferred_setup) ||
!READ_ONCE(fb_helper->open_count))
return 0;
mutex_lock(&fb_helper->lock);
@@ -368,6 +368,7 @@ void drm_fb_helper_prepare(struct drm_device *dev, struct
drm_fb_helper *helper,
INIT_WORK(&helper->dirty_work, drm_fb_helper_dirty_work);
helper->dirty_clip.x1 = helper->dirty_clip.y1 = ~0;
mutex_init(&helper->lock);
+ helper->open_count = 1;
helper->funcs = funcs;
helper->dev = dev;
}
@@ -620,6 +621,53 @@ int drm_fb_helper_defio_init(struct drm_fb_helper
*fb_helper)
}
EXPORT_SYMBOL(drm_fb_helper_defio_init);
+/**
+ * drm_fb_helper_fb_open - implementation for &fb_ops.fb_open
+ * @info: fbdev registered by the helper
+ * @user: 1=userspace, 0=fbcon
+ *
+ * Increase fbdev use count.
+ * If &fb_ops is wrapped in a library, pin the driver module.
+ */
+int drm_fb_helper_fb_open(struct fb_info *info, int user)
+{
+ struct drm_fb_helper *fb_helper = info->par;
+ struct drm_device *dev = fb_helper->dev;
+
+ if (info->fbops->owner != dev->driver->fops->owner) {
+ if (!try_module_get(dev->driver->fops->owner))
+ return -ENODEV;
+ }
+
+ fb_helper->open_count++;
+
+ return 0;
+}
+EXPORT_SYMBOL(drm_fb_helper_fb_open);
+
+/**
+ * drm_fb_helper_fb_release - implementation for &fb_ops.fb_release
+ * @info: fbdev registered by the helper
+ * @user: 1=userspace, 0=fbcon
+ *
+ * Decrease fbdev use count and turn off if there are no users left.
+ * If &fb_ops is wrapped in a library, unpin the driver module.
+ */
+int drm_fb_helper_fb_release(struct fb_info *info, int user)
+{
+ struct drm_fb_helper *fb_helper = info->par;
+ struct drm_device *dev = fb_helper->dev;
+
+ if (!(--fb_helper->open_count))
+ drm_fb_helper_dpms(info, DRM_MODE_DPMS_OFF);
+
+ if (info->fbops->owner != dev->driver->fops->owner)
+ module_put(dev->driver->fops->owner);
+
+ return 0;
+}
+EXPORT_SYMBOL(drm_fb_helper_fb_release);
+
/**
* drm_fb_helper_sys_read - wrapper around fb_sys_read
* @info: fb_info struct pointer
@@ -1436,6 +1484,10 @@ static int drm_fb_helper_single_fb_probe(struct
drm_fb_helper *fb_helper,
if (ret < 0)
return ret;
+ /* Block restore without users if we do track it */
+ if (fb_helper->fbdev->fbops->fb_open == drm_fb_helper_fb_open)
+ fb_helper->open_count = 0;
