On 16:13 Thu 30 May , 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 that
> blanking one of the framebuffers would turn the backlight off for
> all the other framebuffers, since they are likely active to show
> display content. This patch adds logic to record each framebuffer's
> backlight status to determine the backlight device use count and
> whether the backlight should be turned on or off.
>
> Signed-off-by: Liu Ying <Ying.Liu@xxxxxxxxxxxxx>
> ---
> drivers/video/backlight/backlight.c | 23 +++++++++++++++++------
> include/linux/backlight.h | 6 ++++++
> 2 files changed, 23 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
> index c74e7aa..97ea2b8 100644
> --- a/drivers/video/backlight/backlight.c
> +++ b/drivers/video/backlight/backlight.c
> @@ -31,13 +31,14 @@ 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;
>
> /* If we aren't interested in this event, skip it immediately ... */
> if (event != FB_EVENT_BLANK && event != FB_EVENT_CONBLANK)
> @@ -49,11 +50,21 @@ static int fb_notifier_callback(struct notifier_block *self,
> 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);
> + if (bd->props.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;
> + backlight_update_status(bd);
> + }
> + } else if (bd->props.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;
> + backlight_update_status(bd);
> + }
> + }
> }
> mutex_unlock(&bd->ops_lock);
> return 0;
> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index da9a082..5de71a0 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>
>
> @@ -101,6 +102,11 @@ struct backlight_device {
> struct notifier_block fb_notif;
>
> struct device dev;
> +
> + /* Multiple framebuffers may share one backlight device */
> + bool fb_bl_on[FB_MAX];
I don't like such array at all
I understand the fact you will have only on hw backlight for x fb or overlay
but have a static on no
if you want to track all user create a strcut and register it or do more
simple just as a int to count the number of user and shut down it if 0 and
enable it otherwise
Best Regards,
J.
> +
> + int use_count;
> };
>
> static inline void backlight_update_status(struct backlight_device *bd)
> --
> 1.7.1
>
>
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