Re: [PATCH v5 06/10] media: Add registration helpers for V4L2 flash sub-devices
Hi Jacek,
On Fri, Apr 24, 2015 at 12:29:17PM +0200, Jacek Anaszewski wrote:
> Hi Sakari,
>
> On Fri, 24 Apr 2015 00:52:12 +0300
> Sakari Ailus wrote:
>
> > Hi Jacek,
> >
> > Jacek Anaszewski wrote:
> > ...
> > >>> +#define call_flash_op(v4l2_flash, op,
> > >>> arg)\
> > >>> + (has_flash_op(v4l2_flash,
> > >>> op) ? \
> > >>> + v4l2_flash->ops->op(v4l2_flash,
> > >>> arg) : \
> > >>> + -EINVAL)
> > >>> +
> > >>> +static enum led_brightness __intensity_to_led_brightness(
> > >>> + struct v4l2_ctrl *ctrl,
> > >>> + s32 intensity)
> > >>
> > >> Fits on previous line.
> > >>
> > >>> +{
> > >>> + s64 intensity64 = intensity - ctrl->minimum;
> > >>
> > >> intensity, ctrl->step and ctrl->minimum are 32-bit signed integers.
> > >> Do you need a 64-bit integer here?
> > >
> > > step is u64.
> >
> > Nevertheless integer controls will not have values outside the s32
> > range, using a step value that's outside the range makes no sense
> > either. I think you should use s32 instead.
>
> I infer that local u32 variable should be assigned ctrl->step,
> and then used as a divisor.
You could cast explicitly as well. Either is fine for me.
>
> > >
> > >>
> > >>> +
> > >>> + do_div(intensity64, ctrl->step);
> > >>> +
> > >>> + /*
> > >>> +* Indicator LEDs, unlike torch LEDs, are turned on/off
> > >>> basing on
> > >>> +* the state of V4L2_CID_FLASH_INDICATOR_INTENSITY
> > >>> control only.
> > >>> +* Therefore it must be possible to set it to 0 level
> > >>> which in
> > >>> +* the LED subsystem reflects LED_OFF state.
> > >>> +*/
> > >>> + if (ctrl->id != V4L2_CID_FLASH_INDICATOR_INTENSITY)
> > >>> + ++intensity64;
> > >>
> > >> I think the condition could simply be ctrl->minimum instead, that
> > >> way I find it easier to understand what's happening here. I'd
> > >> expect the minimum for non-intensity controls always to be
> > >> non-zero, though, so the end result is the same. Up to you.
> > >
> > > Minimum for indicator control must be 0 to make possible
> > > turning the indicator LED off only with this control.
> >
> > Would torch be still on if the minimum torch current was 0 mA? I'd
> > say no.
> >
> > Although in that case I'd expect the driver to use a different range,
> > and selecting the off mode would then turn it off, I still think
> > that's a better condition than relying on the control id.
>
> I didn't catch your point previously. Probably you was thinking
> about somethig like this:
>
> if (ctrl->minimum)
> ++intensity;
>
> If so, I agree.
Yes, that's what I meant.
>
> > ...
> >
> > >>> +static int v4l2_flash_g_volatile_ctrl(struct v4l2_ctrl *c)
> > >>> +{
> > >>> + struct v4l2_flash *v4l2_flash =
> > >>> v4l2_ctrl_to_v4l2_flash(c);
> > >>> + struct led_classdev_flash *fled_cdev =
> > >>> v4l2_flash->fled_cdev;
> > >>> + bool is_strobing;
> > >>> + int ret;
> > >>> +
> > >>> + switch (c->id) {
> > >>> + case V4L2_CID_FLASH_TORCH_INTENSITY:
> > >>> + case V4L2_CID_FLASH_INDICATOR_INTENSITY:
> > >>> + return
> > >>> v4l2_flash_update_led_brightness(v4l2_flash, c);
> > >>> + case V4L2_CID_FLASH_INTENSITY:
> > >>> + ret = led_update_flash_brightness(fled_cdev);
> > >>> + if (ret < 0)
> > >>> + return ret;
> > >>> + /* no conversion is needed */
> > >>
> > >> Maybe a stupid question, but why is it not needed?
> > >
> > > Because LED Flash class also uses microamperes.
> >
> > Right, I had missed that. It'd be nice if that was said in the
> > comment, it might not be obvious to others either.
>
> OK, I will add the comment.
Thanks!
--
Kind regards,
Sakari Ailus
e-mail: sakari.ai...@iki.fi XMPP: sai...@retiisi.org.uk
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Re: [PATCH v5 06/10] media: Add registration helpers for V4L2 flash sub-devices
Hi Sakari,
On Fri, 24 Apr 2015 00:52:12 +0300
Sakari Ailus wrote:
> Hi Jacek,
>
> Jacek Anaszewski wrote:
> ...
> >>> +#define call_flash_op(v4l2_flash, op,
> >>> arg) \
> >>> + (has_flash_op(v4l2_flash,
> >>> op) ? \
> >>> + v4l2_flash->ops->op(v4l2_flash,
> >>> arg) :\
> >>> + -EINVAL)
> >>> +
> >>> +static enum led_brightness __intensity_to_led_brightness(
> >>> + struct v4l2_ctrl *ctrl,
> >>> + s32 intensity)
> >>
> >> Fits on previous line.
> >>
> >>> +{
> >>> + s64 intensity64 = intensity - ctrl->minimum;
> >>
> >> intensity, ctrl->step and ctrl->minimum are 32-bit signed integers.
> >> Do you need a 64-bit integer here?
> >
> > step is u64.
>
> Nevertheless integer controls will not have values outside the s32
> range, using a step value that's outside the range makes no sense
> either. I think you should use s32 instead.
I infer that local u32 variable should be assigned ctrl->step,
and then used as a divisor.
> >
> >>
> >>> +
> >>> + do_div(intensity64, ctrl->step);
> >>> +
> >>> + /*
> >>> + * Indicator LEDs, unlike torch LEDs, are turned on/off
> >>> basing on
> >>> + * the state of V4L2_CID_FLASH_INDICATOR_INTENSITY
> >>> control only.
> >>> + * Therefore it must be possible to set it to 0 level
> >>> which in
> >>> + * the LED subsystem reflects LED_OFF state.
> >>> + */
> >>> + if (ctrl->id != V4L2_CID_FLASH_INDICATOR_INTENSITY)
> >>> + ++intensity64;
> >>
> >> I think the condition could simply be ctrl->minimum instead, that
> >> way I find it easier to understand what's happening here. I'd
> >> expect the minimum for non-intensity controls always to be
> >> non-zero, though, so the end result is the same. Up to you.
> >
> > Minimum for indicator control must be 0 to make possible
> > turning the indicator LED off only with this control.
>
> Would torch be still on if the minimum torch current was 0 mA? I'd
> say no.
>
> Although in that case I'd expect the driver to use a different range,
> and selecting the off mode would then turn it off, I still think
> that's a better condition than relying on the control id.
I didn't catch your point previously. Probably you was thinking
about somethig like this:
if (ctrl->minimum)
++intensity;
If so, I agree.
> ...
>
> >>> +static int v4l2_flash_g_volatile_ctrl(struct v4l2_ctrl *c)
> >>> +{
> >>> + struct v4l2_flash *v4l2_flash =
> >>> v4l2_ctrl_to_v4l2_flash(c);
> >>> + struct led_classdev_flash *fled_cdev =
> >>> v4l2_flash->fled_cdev;
> >>> + bool is_strobing;
> >>> + int ret;
> >>> +
> >>> + switch (c->id) {
> >>> + case V4L2_CID_FLASH_TORCH_INTENSITY:
> >>> + case V4L2_CID_FLASH_INDICATOR_INTENSITY:
> >>> + return
> >>> v4l2_flash_update_led_brightness(v4l2_flash, c);
> >>> + case V4L2_CID_FLASH_INTENSITY:
> >>> + ret = led_update_flash_brightness(fled_cdev);
> >>> + if (ret < 0)
> >>> + return ret;
> >>> + /* no conversion is needed */
> >>
> >> Maybe a stupid question, but why is it not needed?
> >
> > Because LED Flash class also uses microamperes.
>
> Right, I had missed that. It'd be nice if that was said in the
> comment, it might not be obvious to others either.
OK, I will add the comment.
--
Best Regards,
Jacek Anaszewski
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Re: [PATCH v5 06/10] media: Add registration helpers for V4L2 flash sub-devices
Hi Jacek,
Jacek Anaszewski wrote:
...
>>> +#define call_flash_op(v4l2_flash, op, arg) \
>>> + (has_flash_op(v4l2_flash,
>>> op) ? \
>>> + v4l2_flash->ops->op(v4l2_flash,
>>> arg) : \
>>> + -EINVAL)
>>> +
>>> +static enum led_brightness __intensity_to_led_brightness(
>>> + struct v4l2_ctrl *ctrl,
>>> + s32 intensity)
>>
>> Fits on previous line.
>>
>>> +{
>>> + s64 intensity64 = intensity - ctrl->minimum;
>>
>> intensity, ctrl->step and ctrl->minimum are 32-bit signed integers.
>> Do you need a 64-bit integer here?
>
> step is u64.
Nevertheless integer controls will not have values outside the s32
range, using a step value that's outside the range makes no sense
either. I think you should use s32 instead.
>
>>
>>> +
>>> + do_div(intensity64, ctrl->step);
>>> +
>>> + /*
>>> +* Indicator LEDs, unlike torch LEDs, are turned on/off
>>> basing on
>>> +* the state of V4L2_CID_FLASH_INDICATOR_INTENSITY control
>>> only.
>>> +* Therefore it must be possible to set it to 0 level
>>> which in
>>> +* the LED subsystem reflects LED_OFF state.
>>> +*/
>>> + if (ctrl->id != V4L2_CID_FLASH_INDICATOR_INTENSITY)
>>> + ++intensity64;
>>
>> I think the condition could simply be ctrl->minimum instead, that way
>> I find it easier to understand what's happening here. I'd expect the
>> minimum for non-intensity controls always to be non-zero, though, so
>> the end result is the same. Up to you.
>
> Minimum for indicator control must be 0 to make possible
> turning the indicator LED off only with this control.
Would torch be still on if the minimum torch current was 0 mA? I'd say no.
Although in that case I'd expect the driver to use a different range,
and selecting the off mode would then turn it off, I still think that's
a better condition than relying on the control id.
...
>>> +static int v4l2_flash_g_volatile_ctrl(struct v4l2_ctrl *c)
>>> +{
>>> + struct v4l2_flash *v4l2_flash = v4l2_ctrl_to_v4l2_flash(c);
>>> + struct led_classdev_flash *fled_cdev =
>>> v4l2_flash->fled_cdev;
>>> + bool is_strobing;
>>> + int ret;
>>> +
>>> + switch (c->id) {
>>> + case V4L2_CID_FLASH_TORCH_INTENSITY:
>>> + case V4L2_CID_FLASH_INDICATOR_INTENSITY:
>>> + return
>>> v4l2_flash_update_led_brightness(v4l2_flash, c);
>>> + case V4L2_CID_FLASH_INTENSITY:
>>> + ret = led_update_flash_brightness(fled_cdev);
>>> + if (ret < 0)
>>> + return ret;
>>> + /* no conversion is needed */
>>
>> Maybe a stupid question, but why is it not needed?
>
> Because LED Flash class also uses microamperes.
Right, I had missed that. It'd be nice if that was said in the comment,
it might not be obvious to others either.
--
Kind regards,
Sakari Ailus
sakari.ai...@iki.fi
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Re: [PATCH v5 06/10] media: Add registration helpers for V4L2 flash sub-devices
On Thu, 23 Apr 2015 10:40:09 +0300
Hi Sakari,
Thanks for the review.
Sakari Ailus wrote:
> Hi Jacek,
>
> On Wed, Apr 15, 2015 at 08:48:36AM +0200, Jacek Anaszewski wrote:
> > This patch adds helper functions for registering/unregistering
> > LED Flash class devices as V4L2 sub-devices. The functions should
> > be called from the LED subsystem device driver. In case the
> > support for V4L2 Flash sub-devices is disabled in the kernel
> > config the functions' empty versions will be used.
> >
> > Signed-off-by: Jacek Anaszewski
> > Acked-by: Kyungmin Park
> > Cc: Sakari Ailus
> > Cc: Hans Verkuil
> > ---
> > drivers/media/v4l2-core/Kconfig | 11 +
> > drivers/media/v4l2-core/Makefile |2 +
> > drivers/media/v4l2-core/v4l2-flash.c | 619
> > ++
> > include/media/v4l2-flash.h | 145 4 files
> > changed, 777 insertions(+) create mode 100644
> > drivers/media/v4l2-core/v4l2-flash.c create mode 100644
> > include/media/v4l2-flash.h
> >
> > diff --git a/drivers/media/v4l2-core/Kconfig
> > b/drivers/media/v4l2-core/Kconfig index ba7e21a..f034f1a 100644
> > --- a/drivers/media/v4l2-core/Kconfig
> > +++ b/drivers/media/v4l2-core/Kconfig
> > @@ -44,6 +44,17 @@ config V4L2_MEM2MEM_DEV
> > tristate
> > depends on VIDEOBUF2_CORE
> >
> > +# Used by LED subsystem flash drivers
> > +config V4L2_FLASH_LED_CLASS
> > + tristate "Enable support for Flash sub-devices"
>
> How about: "V4L2 flash API for LED flash class devices"?
OK.
> > + depends on VIDEO_V4L2_SUBDEV_API
> > + depends on LEDS_CLASS_FLASH
> > + ---help---
> > + Say Y here to enable support for Flash sub-devices,
> > which allow
> > + to control LED class devices with use of V4L2 Flash
> > controls.
>
> How about this: "Say Y here to enable V4L2 flash API support for LED
> flash class drivers".
OK.
> > +
> > + When in doubt, say N.
> > +
> > # Used by drivers that need Videobuf modules
> > config VIDEOBUF_GEN
> > tristate
> > diff --git a/drivers/media/v4l2-core/Makefile
> > b/drivers/media/v4l2-core/Makefile index 63d29f2..44e858c 100644
> > --- a/drivers/media/v4l2-core/Makefile
> > +++ b/drivers/media/v4l2-core/Makefile
> > @@ -22,6 +22,8 @@ obj-$(CONFIG_VIDEO_TUNER) += tuner.o
> >
> > obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o
> >
> > +obj-$(CONFIG_V4L2_FLASH_LED_CLASS) += v4l2-flash.o
> > +
> > obj-$(CONFIG_VIDEOBUF_GEN) += videobuf-core.o
> > obj-$(CONFIG_VIDEOBUF_DMA_SG) += videobuf-dma-sg.o
> > obj-$(CONFIG_VIDEOBUF_DMA_CONTIG) += videobuf-dma-contig.o
> > diff --git a/drivers/media/v4l2-core/v4l2-flash.c
> > b/drivers/media/v4l2-core/v4l2-flash.c new file mode 100644
> > index 000..bed2036
> > --- /dev/null
> > +++ b/drivers/media/v4l2-core/v4l2-flash.c
>
> I might rename this as v4l2-flash-led-class.c to match the Kconfig
> option.
Agreed as well.
> > @@ -0,0 +1,619 @@
> > +/*
> > + * V4L2 Flash LED sub-device registration helpers.
> > + *
> > + * Copyright (C) 2015 Samsung Electronics Co., Ltd
> > + * Author: Jacek Anaszewski
> > + *
> > + * This program is free software; you can redistribute it and/or
> > modify
> > + * it under the terms of the GNU General Public License version 2
> > as
> > + * published by the Free Software Foundation.
> > + */
> > +
> > +#include
> > +#include
> > +#include
> > +#include
> > +#include
> > +#include
> > +#include
> > +
> > +#define has_flash_op(v4l2_flash,
> > op) \
> > + (v4l2_flash && v4l2_flash->ops->op)
> > +
> > +#define call_flash_op(v4l2_flash, op, arg) \
> > + (has_flash_op(v4l2_flash,
> > op) ? \
> > + v4l2_flash->ops->op(v4l2_flash,
> > arg) : \
> > + -EINVAL)
> > +
> > +static enum led_brightness __intensity_to_led_brightness(
> > + struct v4l2_ctrl *ctrl,
> > + s32 intensity)
>
> Fits on previous line.
>
> > +{
> > + s64 intensity64 = intensity - ctrl->minimum;
>
> intensity, ctrl->step and ctrl->minimum are 32-bit signed integers.
> Do you need a 64-bit integer here?
step is u64.
>
> > +
> > + do_div(intensity64, ctrl->step);
> > +
> > + /*
> > +* Indicator LEDs, unlike torch LEDs, are turned on/off
> > basing on
> > +* the state of V4L2_CID_FLASH_INDICATOR_INTENSITY control
> > only.
> > +* Therefore it must be possible to set it to 0 level
> > which in
> > +* the LED subsystem reflects LED_OFF state.
> > +*/
> > + if (ctrl->id != V4L2_CID_FLASH_INDICATOR_INTENSITY)
> > + ++intensity64;
>
> I think the condition could simply be ctrl->minimum instead, that way
> I find it easier to understand what's happening here. I'd expect the
> minimum for non-intensity controls always to be non-zero, though, so
> the end result is the same. Up to you.
Minimum for indicator control must be 0 to make possible
turning the indicator LED of
Re: [PATCH v5 06/10] media: Add registration helpers for V4L2 flash sub-devices
Hi Jacek,
On Wed, Apr 15, 2015 at 08:48:36AM +0200, Jacek Anaszewski wrote:
> This patch adds helper functions for registering/unregistering
> LED Flash class devices as V4L2 sub-devices. The functions should
> be called from the LED subsystem device driver. In case the
> support for V4L2 Flash sub-devices is disabled in the kernel
> config the functions' empty versions will be used.
>
> Signed-off-by: Jacek Anaszewski
> Acked-by: Kyungmin Park
> Cc: Sakari Ailus
> Cc: Hans Verkuil
> ---
> drivers/media/v4l2-core/Kconfig | 11 +
> drivers/media/v4l2-core/Makefile |2 +
> drivers/media/v4l2-core/v4l2-flash.c | 619
> ++
> include/media/v4l2-flash.h | 145
> 4 files changed, 777 insertions(+)
> create mode 100644 drivers/media/v4l2-core/v4l2-flash.c
> create mode 100644 include/media/v4l2-flash.h
>
> diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig
> index ba7e21a..f034f1a 100644
> --- a/drivers/media/v4l2-core/Kconfig
> +++ b/drivers/media/v4l2-core/Kconfig
> @@ -44,6 +44,17 @@ config V4L2_MEM2MEM_DEV
> tristate
> depends on VIDEOBUF2_CORE
>
> +# Used by LED subsystem flash drivers
> +config V4L2_FLASH_LED_CLASS
> + tristate "Enable support for Flash sub-devices"
How about: "V4L2 flash API for LED flash class devices"?
> + depends on VIDEO_V4L2_SUBDEV_API
> + depends on LEDS_CLASS_FLASH
> + ---help---
> + Say Y here to enable support for Flash sub-devices, which allow
> + to control LED class devices with use of V4L2 Flash controls.
How about this: "Say Y here to enable V4L2 flash API support for LED flash
class drivers".
> +
> + When in doubt, say N.
> +
> # Used by drivers that need Videobuf modules
> config VIDEOBUF_GEN
> tristate
> diff --git a/drivers/media/v4l2-core/Makefile
> b/drivers/media/v4l2-core/Makefile
> index 63d29f2..44e858c 100644
> --- a/drivers/media/v4l2-core/Makefile
> +++ b/drivers/media/v4l2-core/Makefile
> @@ -22,6 +22,8 @@ obj-$(CONFIG_VIDEO_TUNER) += tuner.o
>
> obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o
>
> +obj-$(CONFIG_V4L2_FLASH_LED_CLASS) += v4l2-flash.o
> +
> obj-$(CONFIG_VIDEOBUF_GEN) += videobuf-core.o
> obj-$(CONFIG_VIDEOBUF_DMA_SG) += videobuf-dma-sg.o
> obj-$(CONFIG_VIDEOBUF_DMA_CONTIG) += videobuf-dma-contig.o
> diff --git a/drivers/media/v4l2-core/v4l2-flash.c
> b/drivers/media/v4l2-core/v4l2-flash.c
> new file mode 100644
> index 000..bed2036
> --- /dev/null
> +++ b/drivers/media/v4l2-core/v4l2-flash.c
I might rename this as v4l2-flash-led-class.c to match the Kconfig option.
> @@ -0,0 +1,619 @@
> +/*
> + * V4L2 Flash LED sub-device registration helpers.
> + *
> + * Copyright (C) 2015 Samsung Electronics Co., Ltd
> + * Author: Jacek Anaszewski
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include
> +#include
> +#include
> +#include
> +#include
> +#include
> +#include
> +
> +#define has_flash_op(v4l2_flash, op) \
> + (v4l2_flash && v4l2_flash->ops->op)
> +
> +#define call_flash_op(v4l2_flash, op, arg) \
> + (has_flash_op(v4l2_flash, op) ? \
> + v4l2_flash->ops->op(v4l2_flash, arg) : \
> + -EINVAL)
> +
> +static enum led_brightness __intensity_to_led_brightness(
> + struct v4l2_ctrl *ctrl,
> + s32 intensity)
Fits on previous line.
> +{
> + s64 intensity64 = intensity - ctrl->minimum;
intensity, ctrl->step and ctrl->minimum are 32-bit signed integers. Do you
need a 64-bit integer here?
> +
> + do_div(intensity64, ctrl->step);
> +
> + /*
> + * Indicator LEDs, unlike torch LEDs, are turned on/off basing on
> + * the state of V4L2_CID_FLASH_INDICATOR_INTENSITY control only.
> + * Therefore it must be possible to set it to 0 level which in
> + * the LED subsystem reflects LED_OFF state.
> + */
> + if (ctrl->id != V4L2_CID_FLASH_INDICATOR_INTENSITY)
> + ++intensity64;
I think the condition could simply be ctrl->minimum instead, that way I find
it easier to understand what's happening here. I'd expect the minimum for
non-intensity controls always to be non-zero, though, so the end result is
the same. Up to you.
> +
> + return intensity64;
> +}
> +
> +static s32 __led_brightness_to_intensity(struct v4l2_ctrl *ctrl,
> + enum led_brightness brightness)
> +{
> + /*
> + * Indicator LEDs, unlike torch LEDs, are turned on/off basing on
> + * the state of V4L2_CID_FLASH_INDICATOR_INTENSITY control only.
> + * Do not decrement brightness read from the LED subsystem for
> + * indicator LED as it may equal 0.
[PATCH v5 06/10] media: Add registration helpers for V4L2 flash sub-devices
This patch adds helper functions for registering/unregistering
LED Flash class devices as V4L2 sub-devices. The functions should
be called from the LED subsystem device driver. In case the
support for V4L2 Flash sub-devices is disabled in the kernel
config the functions' empty versions will be used.
Signed-off-by: Jacek Anaszewski
Acked-by: Kyungmin Park
Cc: Sakari Ailus
Cc: Hans Verkuil
---
drivers/media/v4l2-core/Kconfig | 11 +
drivers/media/v4l2-core/Makefile |2 +
drivers/media/v4l2-core/v4l2-flash.c | 619 ++
include/media/v4l2-flash.h | 145
4 files changed, 777 insertions(+)
create mode 100644 drivers/media/v4l2-core/v4l2-flash.c
create mode 100644 include/media/v4l2-flash.h
diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig
index ba7e21a..f034f1a 100644
--- a/drivers/media/v4l2-core/Kconfig
+++ b/drivers/media/v4l2-core/Kconfig
@@ -44,6 +44,17 @@ config V4L2_MEM2MEM_DEV
tristate
depends on VIDEOBUF2_CORE
+# Used by LED subsystem flash drivers
+config V4L2_FLASH_LED_CLASS
+ tristate "Enable support for Flash sub-devices"
+ depends on VIDEO_V4L2_SUBDEV_API
+ depends on LEDS_CLASS_FLASH
+ ---help---
+ Say Y here to enable support for Flash sub-devices, which allow
+ to control LED class devices with use of V4L2 Flash controls.
+
+ When in doubt, say N.
+
# Used by drivers that need Videobuf modules
config VIDEOBUF_GEN
tristate
diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile
index 63d29f2..44e858c 100644
--- a/drivers/media/v4l2-core/Makefile
+++ b/drivers/media/v4l2-core/Makefile
@@ -22,6 +22,8 @@ obj-$(CONFIG_VIDEO_TUNER) += tuner.o
obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o
+obj-$(CONFIG_V4L2_FLASH_LED_CLASS) += v4l2-flash.o
+
obj-$(CONFIG_VIDEOBUF_GEN) += videobuf-core.o
obj-$(CONFIG_VIDEOBUF_DMA_SG) += videobuf-dma-sg.o
obj-$(CONFIG_VIDEOBUF_DMA_CONTIG) += videobuf-dma-contig.o
diff --git a/drivers/media/v4l2-core/v4l2-flash.c
b/drivers/media/v4l2-core/v4l2-flash.c
new file mode 100644
index 000..bed2036
--- /dev/null
+++ b/drivers/media/v4l2-core/v4l2-flash.c
@@ -0,0 +1,619 @@
+/*
+ * V4L2 Flash LED sub-device registration helpers.
+ *
+ * Copyright (C) 2015 Samsung Electronics Co., Ltd
+ * Author: Jacek Anaszewski
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+
+#define has_flash_op(v4l2_flash, op) \
+ (v4l2_flash && v4l2_flash->ops->op)
+
+#define call_flash_op(v4l2_flash, op, arg) \
+ (has_flash_op(v4l2_flash, op) ? \
+ v4l2_flash->ops->op(v4l2_flash, arg) : \
+ -EINVAL)
+
+static enum led_brightness __intensity_to_led_brightness(
+ struct v4l2_ctrl *ctrl,
+ s32 intensity)
+{
+ s64 intensity64 = intensity - ctrl->minimum;
+
+ do_div(intensity64, ctrl->step);
+
+ /*
+* Indicator LEDs, unlike torch LEDs, are turned on/off basing on
+* the state of V4L2_CID_FLASH_INDICATOR_INTENSITY control only.
+* Therefore it must be possible to set it to 0 level which in
+* the LED subsystem reflects LED_OFF state.
+*/
+ if (ctrl->id != V4L2_CID_FLASH_INDICATOR_INTENSITY)
+ ++intensity64;
+
+ return intensity64;
+}
+
+static s32 __led_brightness_to_intensity(struct v4l2_ctrl *ctrl,
+enum led_brightness brightness)
+{
+ /*
+* Indicator LEDs, unlike torch LEDs, are turned on/off basing on
+* the state of V4L2_CID_FLASH_INDICATOR_INTENSITY control only.
+* Do not decrement brightness read from the LED subsystem for
+* indicator LED as it may equal 0. For torch LEDs this function
+* is called only when V4L2_FLASH_LED_MODE_TORCH is set and the
+* brightness read is guaranteed to be greater than 0. In the mode
+* V4L2_FLASH_LED_MODE_NONE the cached torch intensity value is used.
+*/
+ if (ctrl->id != V4L2_CID_FLASH_INDICATOR_INTENSITY)
+ --brightness;
+
+ return (brightness * ctrl->step) + ctrl->minimum;
+}
+
+static void v4l2_flash_set_led_brightness(struct v4l2_flash *v4l2_flash,
+ struct v4l2_ctrl *ctrl)
+{
+ struct v4l2_ctrl **ctrls = v4l2_flash->ctrls;
+ enum led_brightness brightness;
+
+ if (has_flash_op(v4l2_flash, intensity_to_led_brightness))
+ brightness = call_flash_op(v4l2_flash,
+ intensity_to_led_brightness,
+
