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Date: Wed, 22 Jan 2014 14:09:45 +0900
From: Jingoo Han <jg1.han@...sung.com>
To: 'Liu Ying' <Ying.Liu@...escale.com>
Cc: linux-fbdev@...r.kernel.org,
'linux-kernel' <linux-kernel@...r.kernel.org>,
'DRI mailing list' <dri-devel@...ts.freedesktop.org>,
plagnioj@...osoft.com, tomi.valkeinen@...com,
'Jingoo Han' <jg1.han@...sung.com>
Subject: Re: [PATCH v2] backlight: turn backlight on/off when necessary
On Wednesday, January 22, 2014 2:04 PM, Liu Ying wrote:
>
> Ping...
>
> Regards,
> Liu Ying
Please, don't send the ping within 2 days.
It is not a good practice. You sent the v1 patch 6 months ago.
However, why I should review the patch within 2 days?
Please wait.
Best regards,
Jingoo Han
>
> 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@...escale.com>
> > ---
> > 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
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