Re: [Intel-gfx] [RFC v4 21/25] drm/fb-helper: Add drm_fb_helper_fb_open/release()

2018-04-17 Thread Daniel Vetter 
On Mon, Apr 16, 2018 at 06:10:07PM +0200, Noralf Trønnes wrote:
> 
> 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 
> > > ---
> > >   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(_helper->lock);
> > > @@ -368,6 +368,7 @@ void drm_fb_helper_prepare(struct drm_device *dev, 
> > > struct drm_fb_helper *helper,
> > >   INIT_WORK(>dirty_work, drm_fb_helper_dirty_work);
> > >   helper->dirty_clip.x1 = helper->dirty_clip.y1 = ~0;
> > >   mutex_init(>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 _ops.fb_open
> > > + * @info: fbdev registered by the helper
> > > + * @user: 1=userspace, 0=fbcon
> > > + *
> > > + * Increase fbdev use count.
> > > + * If _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 _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 _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.

Ah I missed that. I think having the fbops->fb_op == drm_fb_helper_fb_open
check in the restore function itself, plus a big comment explaining what
you're doing, would be clearer. So instead of always checking the
open_count, only check it when this helper is in use.

> Ofc I could have changed all drivers to use

Re: [Intel-gfx] [RFC v4 21/25] drm/fb-helper: Add drm_fb_helper_fb_open/release()

2018-04-16 Thread Noralf Trønnes 


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 
---
  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(_helper->lock);

@@ -368,6 +368,7 @@ void drm_fb_helper_prepare(struct drm_device *dev, struct 
drm_fb_helper *helper,
INIT_WORK(>dirty_work, drm_fb_helper_dirty_work);
helper->dirty_clip.x1 = helper->dirty_clip.y1 = ~0;
mutex_init(>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 _ops.fb_open
+ * @info: fbdev registered by the helper
+ * @user: 1=userspace, 0=fbcon
+ *
+ * Increase fbdev use count.
+ * If _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 _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 _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

Re: [Intel-gfx] [RFC v4 21/25] drm/fb-helper: Add drm_fb_helper_fb_open/release()

2018-04-16 Thread 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 
> ---
>  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(_helper->lock);
> @@ -368,6 +368,7 @@ void drm_fb_helper_prepare(struct drm_device *dev, struct 
> drm_fb_helper *helper,
>   INIT_WORK(>dirty_work, drm_fb_helper_dirty_work);
>   helper->dirty_clip.x1 = helper->dirty_clip.y1 = ~0;
>   mutex_init(>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 _ops.fb_open
> + * @info: fbdev registered by the helper
> + * @user: 1=userspace, 0=fbcon
> + *
> + * Increase fbdev use count.
> + * If _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 _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 _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.

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

[RFC v4 21/25] drm/fb-helper: Add drm_fb_helper_fb_open/release()

2018-04-14 Thread Noralf Trønnes 
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 
---
 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(_helper->lock);
@@ -368,6 +368,7 @@ void drm_fb_helper_prepare(struct drm_device *dev, struct 
drm_fb_helper *helper,
INIT_WORK(>dirty_work, drm_fb_helper_dirty_work);
helper->dirty_clip.x1 = helper->dirty_clip.y1 = ~0;
mutex_init(>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 _ops.fb_open
+ * @info: fbdev registered by the helper
+ * @user: 1=userspace, 0=fbcon
+ *
+ * Increase fbdev use count.
+ * If _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 _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 _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;
+
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 _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

[RFC v4 21/25] drm/fb-helper: Add drm_fb_helper_fb_open/release()

2018-04-13 Thread Noralf Trønnes 
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 
---
 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(_helper->lock);
@@ -368,6 +368,7 @@ void drm_fb_helper_prepare(struct drm_device *dev, struct 
drm_fb_helper *helper,
INIT_WORK(>dirty_work, drm_fb_helper_dirty_work);
helper->dirty_clip.x1 = helper->dirty_clip.y1 = ~0;
mutex_init(>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 _ops.fb_open
+ * @info: fbdev registered by the helper
+ * @user: 1=userspace, 0=fbcon
+ *
+ * Increase fbdev use count.
+ * If _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 _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 _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;
+
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 _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

[RFC v4 21/25] drm/fb-helper: Add drm_fb_helper_fb_open/release()

2018-04-12 Thread Noralf Trønnes 
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 
---
 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(_helper->lock);
@@ -368,6 +368,7 @@ void drm_fb_helper_prepare(struct drm_device *dev, struct 
drm_fb_helper *helper,
INIT_WORK(>dirty_work, drm_fb_helper_dirty_work);
helper->dirty_clip.x1 = helper->dirty_clip.y1 = ~0;
mutex_init(>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 _ops.fb_open
+ * @info: fbdev registered by the helper
+ * @user: 1=userspace, 0=fbcon
+ *
+ * Increase fbdev use count.
+ * If _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 _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 _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;
+
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 _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