Ping... Regards, Liu Ying On 01/20/2014 12:52 PM, Liu Ying wrote: > We don't have to turn backlight on/off everytime a blanking > or unblanking event comes because the backlight status may > have already been what we want. Another thought is that one > backlight device may be shared by multiple framebuffers. We > don't hope blanking one of the framebuffers may turn the > backlight off for all the other framebuffers, since they are > likely being active to display something. This patch adds > some logics to record each framebuffer's backlight usage to > determine the backlight device use count and whether the > backlight should be turned on or off. To be more specific, > only one unblank operation on a certain blanked framebuffer > may increase the backlight device's use count by one, while > one blank operation on a certain unblanked framebuffer may > decrease the use count by one, because the userspace is > likely to unblank a unblanked framebuffer or blank a blanked > framebuffer. > > Signed-off-by: Liu Ying <Ying.Liu@xxxxxxxxxxxxx> > --- > v1 can be found at https://lkml.org/lkml/2013/5/30/139 > > v1->v2: > * Make the commit message be more specific about the condition > in which backlight device use count can be increased/decreased. > * Correct the setting for bd->props.fb_blank. > > drivers/video/backlight/backlight.c | 28 +++++++++++++++++++++------- > include/linux/backlight.h | 6 ++++++ > 2 files changed, 27 insertions(+), 7 deletions(-) > > diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c > index 5d05555..42044be 100644 > --- a/drivers/video/backlight/backlight.c > +++ b/drivers/video/backlight/backlight.c > @@ -34,13 +34,15 @@ static const char *const backlight_types[] = { > defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE)) > /* This callback gets called when something important happens inside a > * framebuffer driver. We're looking if that important event is blanking, > - * and if it is, we're switching backlight power as well ... > + * and if it is and necessary, we're switching backlight power as well ... > */ > static int fb_notifier_callback(struct notifier_block *self, > unsigned long event, void *data) > { > struct backlight_device *bd; > struct fb_event *evdata = data; > + int node = evdata->info->node; > + int fb_blank = 0; > > /* If we aren't interested in this event, skip it immediately ... */ > if (event != FB_EVENT_BLANK && event != FB_EVENT_CONBLANK) > @@ -51,12 +53,24 @@ static int fb_notifier_callback(struct notifier_block *self, > if (bd->ops) > if (!bd->ops->check_fb || > bd->ops->check_fb(bd, evdata->info)) { > - bd->props.fb_blank = *(int *)evdata->data; > - if (bd->props.fb_blank == FB_BLANK_UNBLANK) > - bd->props.state &= ~BL_CORE_FBBLANK; > - else > - bd->props.state |= BL_CORE_FBBLANK; > - backlight_update_status(bd); > + fb_blank = *(int *)evdata->data; > + if (fb_blank == FB_BLANK_UNBLANK && > + !bd->fb_bl_on[node]) { > + bd->fb_bl_on[node] = true; > + if (!bd->use_count++) { > + bd->props.state &= ~BL_CORE_FBBLANK; > + bd->props.fb_blank = FB_BLANK_UNBLANK; > + backlight_update_status(bd); > + } > + } else if (fb_blank != FB_BLANK_UNBLANK && > + bd->fb_bl_on[node]) { > + bd->fb_bl_on[node] = false; > + if (!(--bd->use_count)) { > + bd->props.state |= BL_CORE_FBBLANK; > + bd->props.fb_blank = FB_BLANK_POWERDOWN; > + backlight_update_status(bd); > + } > + } > } > mutex_unlock(&bd->ops_lock); > return 0; > diff --git a/include/linux/backlight.h b/include/linux/backlight.h > index 5f9cd96..7264742 100644 > --- a/include/linux/backlight.h > +++ b/include/linux/backlight.h > @@ -9,6 +9,7 @@ > #define _LINUX_BACKLIGHT_H > > #include <linux/device.h> > +#include <linux/fb.h> > #include <linux/mutex.h> > #include <linux/notifier.h> > > @@ -104,6 +105,11 @@ struct backlight_device { > struct list_head entry; > > struct device dev; > + > + /* Multiple framebuffers may share one backlight device */ > + bool fb_bl_on[FB_MAX]; > + > + int use_count; > }; > > static inline void backlight_update_status(struct backlight_device *bd) > -- > 1.7.9.5 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
