Den 16.04.2018 10.46, skrev Daniel Vetter:
On Sat, Apr 14, 2018 at 01:53:14PM +0200, Noralf Trønnes wrote:
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 <noralf@xxxxxxxxxxx>
---
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;
Since we kzcalloc, isn't this entirely redundant? Looks confusing to me at
least.
I have to keep the existing restore behaviour for those that don't use
drm_fb_helper_fb_open(). I do this by setting fb_helper->open_count = 1
in drm_fb_helper_prepare(). I have tried to give a describtion in the
@open_count docs.
Ofc I could have changed all drivers to use drm_fb_helper_fb_open(), but
I think that time is better spent moving drivers over to generic fbdev
instead.
Noralf.
Otherwise looks all reasonable.
-Daniel
+
strcpy(fb_helper->fb->comm, "[fbcon]");
return 0;
}
diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
index 5f66f253a97b..330983975d5e 100644
--- a/include/drm/drm_fb_helper.h
+++ b/include/drm/drm_fb_helper.h
@@ -184,6 +184,22 @@ struct drm_fb_helper {
* See also: @deferred_setup
*/
int preferred_bpp;
+
+ /**
+ * @open_count:
+ *
+ * Keeps track of fbdev use to know when to not restore fbdev and to
+ * disable the pipeline when the last user is gone.
+ *
+ * Drivers that use drm_fb_helper_fb_open() as their \.fb_open
+ * callback will get an initial value of 0 and get restore based on
+ * actual use. Others will get an initial value of 1 which means that
+ * fbdev will always be restored. Drivers that call
+ * drm_fb_helper_fb_open() in their \.fb_open, thus needs to set the
+ * initial value to 0 themselves in their &drm_fb_helper_funcs->fb_probe
+ * callback.
+ */
+ unsigned int open_count;
};
/**
@@ -230,6 +246,9 @@ void drm_fb_helper_deferred_io(struct fb_info *info,
struct list_head *pagelist);
int drm_fb_helper_defio_init(struct drm_fb_helper *fb_helper);
+int drm_fb_helper_fb_open(struct fb_info *info, int user);
+int drm_fb_helper_fb_release(struct fb_info *info, int user);
+
ssize_t drm_fb_helper_sys_read(struct fb_info *info, char __user *buf,
size_t count, loff_t *ppos);
ssize_t drm_fb_helper_sys_write(struct fb_info *info, const char __user *buf,
@@ -376,6 +395,16 @@ static inline int drm_fb_helper_defio_init(struct drm_fb_helper *fb_helper)
return -ENODEV;
}
+static inline int drm_fb_helper_fb_open(struct fb_info *info, int user)
+{
+ return -ENODEV;
+}
+
+static inline int drm_fb_helper_fb_release(struct fb_info *info, int user)
+{
+ return -ENODEV;
+}
+
static inline ssize_t drm_fb_helper_sys_read(struct fb_info *info,
char __user *buf, size_t count,
loff_t *ppos)
--
2.15.1
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