diff mbox

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

Message ID 20180414115318.14500-22-noralf@tronnes.org (mailing list archive)
State New, archived
Headers show

Commit Message

Noralf Trønnes April 14, 2018, 11:53 a.m. UTC
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@tronnes.org>
---
 drivers/gpu/drm/drm_fb_helper.c | 54 ++++++++++++++++++++++++++++++++++++++++-
 include/drm/drm_fb_helper.h     | 29 ++++++++++++++++++++++
 2 files changed, 82 insertions(+), 1 deletion(-)

Comments

Daniel Vetter April 16, 2018, 8:46 a.m. UTC | #1
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@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;

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 &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
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
Noralf Trønnes April 16, 2018, 4:10 p.m. UTC | #2
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@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;
> 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
>>
>> _______________________________________________
>> Intel-gfx mailing list
>> Intel-gfx@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
Daniel Vetter April 17, 2018, 8:14 a.m. UTC | #3
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 <noralf@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;
> > 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 drm_fb_helper_fb_open(), but
> I think that time is better spent moving drivers over to generic fbdev
> instead.

Yeah FIXME (plus maybe todo.rst entry, this is perfect starting task
fodder) is totally good enough.
-Daniel

> 
> 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
> > > 
> > > _______________________________________________
> > > Intel-gfx mailing list
> > > Intel-gfx@lists.freedesktop.org
> > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
diff mbox

Patch

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;
+
 	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)