Dear Lee,
> On Tue, 08 Nov 2016, Lukasz Majewski wrote:
>
> > Dear All,
> >
> > > The commit a55944ca82d2 ("backlight: update bd state & fb_blank
> > > properties when necessary") has posed some extra 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.
> >
> > COmments/acks are more than welcome :-)
>
> Ah, it looks like you dropped Jingoo from the list!
> I can only apologize for such situation.... strange mistake. > I'll reply to the original mail with him in CC. Thank you for your help. Best regards, Lukasz Majewski > > > > Signed-off-by: Lukasz Majewski <[email protected]> > > > --- > > > The patch has been tested on i.MX6q with 4.9-rc3 > > > SHA1: a909d3e636995ba7c349e2ca5dbb528154d4ac30 > > > --- > > > Changes for v2: > > > - Update commit message with proper other commit reference > > > > > > --- > > > 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 1261400..6859ba0 100644 > > > --- a/drivers/video/backlight/pwm_bl.c > > > +++ b/drivers/video/backlight/pwm_bl.c > > > @@ -202,7 +202,7 @@ 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); @@ -348,6 +348,14 @@ 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); > > > > >
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