lkml.org 
[lkml]   [2016]   [Oct]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_probe()
Date
On Monday, October 24, 2016, Lukasz Majewski wrote:
>
> Hi Jingoo,
>
> > On Saturday, October 22, 2016, Lukasz Majewski wrote:
> > >
> > > The commit: a55944ca82d287ca099ca90413af857af9086773 has posed some
> > > extra

Please add the 'subject' of patch as below.

The commit a55944ca82d2 ("backlight: update bd state & fb_blank properties when necessary ")
has posted some extra.

Best regards,
Jingoo Han


> >
> > Please add the subject of the patch, in order to let people know
> > which patch you mention exactly. Please loot at other commits that
> > fixed bugs or behavior
> > of other patches.
>
> Thanks for the tip.
>
> The mentioned patch:
>
> commit a55944ca82d287ca099ca90413af857af9086773
> Author: Liu Ying <Ying.Liu@freescale.com>
> Date: Thu Apr 3 14:48:54 2014 -0700
>
> backlight: update bd state & fb_blank properties when necessary
>
> We don't have to update the state and fb_blank properties of a
> backlight
> device every time a blanking or unblanking event comes because they
> may
> have already been what we want. Another thought is that one backlight
> device may be shared by multiple framebuffers. The backlight driver
> should take the backlight device as a resource shared by all the
> associated framebuffers.
>
> This patch adds some logic to record each framebuffer's backlight
> usage
> to determine the backlight device use count and whether the two
> properties should be updated or not. 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 an unblanked framebuffer or blank a
> blanked framebuffer.
>
>
> Could you provide more feedback regarding provided fix?
>
> Thanks in advance,
>
> Łukasz Majewski
>
> >
> > > restrictions on blanking and unblanking frame buffer device.
> > >
> > > Unfortunately, pwm_bl driver's probe did not initialize members of
> > > struct backlight_device necessary for further blank/unblank
> > > operation.
> > >
> > > This code in case of initial unblank of backlight device (default
> > > behaviour) sets use_count to 1 and marks this particular backlight
> > > device as used by all available fb devices (since it is not known
> > > during probe how much and which fb devices will be assigned).
> > >
> > > Without this code, the backlight works properly until one tries to
> > > blank it manually from sysfs with "echo 1
> > > > /sys/class/graphics/fb0/blank". Since fb_bl_on[0] and use_count
> > > > were both set to 0, the logic at
> > > fb_notifier_callback (@backlight.c) thought that we didn't turn on
> > > (unblanked) the backlight device and refuses to disable (blank) it.
> > > As a result we see garbage from fb displayed.
> > >
> > >
> > > Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>
> > > ---
> > > The patch has been tested on i.MX6q with vanilla 4.7 and 4.8
> > > kernels. It applies on 4.9-rcX SHA1:
> > > dcd4693cf47801b7d988ea897519de90dfd25d17.
> > >
> > > ---
> > > drivers/video/backlight/pwm_bl.c | 10 +++++++++-
> > > 1 file changed, 9 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/video/backlight/pwm_bl.c
> > > b/drivers/video/backlight/pwm_bl.c
> > > index 8040fd6..def39e8 100644
> > > --- a/drivers/video/backlight/pwm_bl.c
> > > +++ b/drivers/video/backlight/pwm_bl.c
> > > @@ -203,7 +203,7 @@ static int pwm_backlight_probe(struct
> > > platform_device *pdev)
> > > struct pwm_bl_data *pb;
> > > int initial_blank = FB_BLANK_UNBLANK;
> > > struct pwm_args pargs;
> > > - int ret;
> > > + int ret, i;
> > >
> > > if (!data) {
> > > ret = pwm_backlight_parse_dt(&pdev->dev,
> > > &defdata); @@ - 349,6 +349,14 @@ static int
> > > pwm_backlight_probe(struct platform_device *pdev)
> > >
> > > bl->props.brightness = data->dft_brightness;
> > > bl->props.power = initial_blank;
> > > +
> > > + if (initial_blank == FB_BLANK_UNBLANK) {
> > > + for (i = 0; i < FB_MAX; i++)
> > > + bl->fb_bl_on[i] = true;
> > > +
> > > + bl->use_count = 1;
> > > + }
> > > +
> > > backlight_update_status(bl);
> > >
> > > platform_set_drvdata(pdev, bl);
> > > --
> > > 2.1.4
> >
> >


\
 
 \ /
  Last update: 2016-10-26 00:48    [W:0.065 / U:0.808 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site