Re: [RFC] drm: emit change events when mode config changes

[Chris Bandy <cbandy@jbandy.com>]

On 04/14/2011 12:42 PM, Jesse Barnes wrote:
> We've already seen that apps want to monitor the display config, and
> some (like upowerd) poll for changes since we don't provide a
> notification for general mode config changes, just hotplug events.  So
> add a new drm event, with CHANGE=1 set in the event, to allow for it.
>
> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
>
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index 4c95b5f..174ee64 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -1589,6 +1589,8 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
>  	set.fb = fb;
>  	ret = crtc->funcs->set_config(&set);
>  
> +	drm_sysfs_change_event(dev);
> +
>  out:
>  	kfree(connector_set);
>  	mutex_unlock(&dev->mode_config.mutex);
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 9507204..df946d4 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -822,6 +822,8 @@ int drm_fb_helper_set_par(struct fb_info *info)
>  			return ret;
>  		}
>  	}
> +
> +	drm_sysfs_change_event(dev);
>  	mutex_unlock(&dev->mode_config.mutex);
>  
>  	if (fb_helper->delayed_hotplug) {
> diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
> index 2eee8e0..fd3af31 100644
> --- a/drivers/gpu/drm/drm_sysfs.c
> +++ b/drivers/gpu/drm/drm_sysfs.c
> @@ -467,9 +467,9 @@ EXPORT_SYMBOL(drm_sysfs_connector_remove);
>   * drm_sysfs_hotplug_event - generate a DRM uevent
>   * @dev: DRM device
>   *
> - * Send a uevent for the DRM device specified by @dev.  Currently we only
> - * set HOTPLUG=1 in the uevent environment, but this could be expanded to
> - * deal with other types of events.
> + * Send a uevent for the DRM device specified by @dev.  Set HOTPLUG=1 in the
> + * event to indicate a display config change occurred, probably due to a
> + * display being added or removed.
>   */
>  void drm_sysfs_hotplug_event(struct drm_device *dev)
>  {
> @@ -483,6 +483,24 @@ void drm_sysfs_hotplug_event(struct drm_device *dev)
>  EXPORT_SYMBOL(drm_sysfs_hotplug_event);
>  
>  /**
> + * drm_sysfs_change_event - generate a DRM uevent indicating a display config change
> + * @dev: DRM device
> + *
> + * Send a uevent for the DRM device specified by @dev.  Set CHANGE=1 to
> + * indicate that a userspace initiated display configuration change occurred.
> + */
> +void drm_sysfs_change_event(struct drm_device *dev)
> +{
> +	char *event_string = "CHANGE=1";
> +	char *envp[] = { event_string, NULL };
> +
> +	DRM_DEBUG("generating hotplug event\n");

Should be "change event" here?

> +
> +	kobject_uevent_env(&dev->primary->kdev.kobj, KOBJ_CHANGE, envp);
> +}
> +EXPORT_SYMBOL(drm_sysfs_change_event);
> +
> +/**
>   * drm_sysfs_device_add - adds a class device to sysfs for a character driver
>   * @dev: DRM device to be added
>   * @head: DRM head in question
> diff --git a/include/drm/drmP.h b/include/drm/drmP.h
> index ad5770f..3aff8fc 100644
> --- a/include/drm/drmP.h
> +++ b/include/drm/drmP.h
> @@ -1506,6 +1506,7 @@ extern struct class *drm_sysfs_create(struct module *owner, char *name);
>  extern void drm_sysfs_destroy(void);
>  extern int drm_sysfs_device_add(struct drm_minor *minor);
>  extern void drm_sysfs_hotplug_event(struct drm_device *dev);
> +extern void drm_sysfs_change_event(struct drm_device *dev);
>  extern void drm_sysfs_device_remove(struct drm_minor *minor);
>  extern char *drm_get_connector_status_name(enum drm_connector_status status);
>  extern int drm_sysfs_connector_add(struct drm_connector *connector);
>
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priority.Virtualization can reduce costs, simplify management, and improve 
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