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[PATCH v2 RESEND] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_probe()

Started byLukasz Majewski <l.majewski@majess.pl>
First post2016-12-27 00:10 +0100
Last post2017-01-13 01:30 +0100
Articles 5 — 3 participants

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  [PATCH v2 RESEND] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_probe() Lukasz Majewski <l.majewski@majess.pl> - 2016-12-27 00:10 +0100
    Re: [PATCH v2 RESEND] video: backlight: pwm_bl: Initialize  fb_bl_on[x] and use_count during pwm_backlight_probe() Lukasz Majewski <l.majewski@majess.pl> - 2017-01-03 08:10 +0100
    Re: [PATCH v2 RESEND] video: backlight: pwm_bl: Initialize  fb_bl_on[x] and use_count during pwm_backlight_probe() Lee Jones <lee.jones@linaro.org> - 2017-01-03 09:30 +0100
      Re: [PATCH v2 RESEND] video: backlight: pwm_bl: Initialize  fb_bl_on[x] and use_count during pwm_backlight_probe() Lukasz Majewski <l.majewski@majess.pl> - 2017-01-06 15:30 +0100
      Re: [PATCH v2 RESEND] video: backlight: pwm_bl: Initialize  fb_bl_on[x] and use_count during pwm_backlight_probe() Lukasz Majewski <lukma@denx.de> - 2017-01-13 01:30 +0100

#1547413 — [PATCH v2 RESEND] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_probe()

FromLukasz Majewski <l.majewski@majess.pl>
Date2016-12-27 00:10 +0100
Subject[PATCH v2 RESEND] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_probe()
Message-ID<sSMyZ-2EX-13@gated-at.bofh.it>
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.

Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>
---
The patch has been tested on i.MX6q with vanilla 4.9 kernel.
It applies on 4.10-rc1.
---
 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);
-- 
2.1.4

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#1549573 — Re: [PATCH v2 RESEND] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_probe()

FromLukasz Majewski <l.majewski@majess.pl>
Date2017-01-03 08:10 +0100
SubjectRe: [PATCH v2 RESEND] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_probe()
Message-ID<sVrol-2F9-7@gated-at.bofh.it>
In reply to#1547413

[Multipart message — attachments visible in raw view] — view raw

Dear All,

A gentle ping for this patch :-)

We had a discussion about it in a following thread:

http://patchwork.ozlabs.org/patch/689786/

According to comments, I've prepared v2 of this commit and also resend
it recently:

http://patchwork.ozlabs.org/patch/708844/

Any new comments?


Thanks in advance,
Łukasz Majewski

> 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.
> 
> Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>
> ---
> The patch has been tested on i.MX6q with vanilla 4.9 kernel.
> It applies on 4.10-rc1.
> ---
>  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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#1549599 — Re: [PATCH v2 RESEND] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_probe()

FromLee Jones <lee.jones@linaro.org>
Date2017-01-03 09:30 +0100
SubjectRe: [PATCH v2 RESEND] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_probe()
Message-ID<sVsDM-3nL-17@gated-at.bofh.it>
In reply to#1547413
Thierry, Jingoo,

Please respond to Lukasz.

On Mon, 26 Dec 2016, Lukasz Majewski wrote:

> 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.
> 
> Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>
> ---
> The patch has been tested on i.MX6q with vanilla 4.9 kernel.
> It applies on 4.10-rc1.
> ---
>  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);

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

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#1552839 — Re: [PATCH v2 RESEND] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_probe()

FromLukasz Majewski <l.majewski@majess.pl>
Date2017-01-06 15:30 +0100
SubjectRe: [PATCH v2 RESEND] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_probe()
Message-ID<sWDGO-3a7-17@gated-at.bofh.it>
In reply to#1549599

[Multipart message — attachments visible in raw view] — view raw

Hi Lee, Thierry, Jingoo,

> 
> Please respond to Lukasz.

Gentel Ping....

Best regards,
Łukasz Majewski

> 
> On Mon, 26 Dec 2016, Lukasz Majewski wrote:
> 
> > 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.
> > 
> > Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>
> > ---
> > The patch has been tested on i.MX6q with vanilla 4.9 kernel.
> > It applies on 4.10-rc1.
> > ---
> >  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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#1557929 — Re: [PATCH v2 RESEND] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_probe()

FromLukasz Majewski <lukma@denx.de>
Date2017-01-13 01:30 +0100
SubjectRe: [PATCH v2 RESEND] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_probe()
Message-ID<sYXUK-2kB-3@gated-at.bofh.it>
In reply to#1549599
Dear All,

> Thierry, Jingoo,
> 
> Please respond to Lukasz.

Yes, your response is more than welcome....... :-)

Thanks in advance,

Łukasz Majewski

> 
> On Mon, 26 Dec 2016, Lukasz Majewski wrote:
> 
> > 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.
> > 
> > Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>
> > ---
> > The patch has been tested on i.MX6q with vanilla 4.9 kernel.
> > It applies on 4.10-rc1.
> > ---
> >  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);
> 

Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de

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