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[PATCH 2/3] drm/panel: ld9040: Register a backlight device

Paul Cercueil posted 3 patches 2 years, 7 months ago
[PATCH 2/3] drm/panel: ld9040: Register a backlight device
Posted by Paul Cercueil 2 years, 7 months ago 
Register a backlight device to be able to switch between all the gamma
levels.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 drivers/gpu/drm/panel/panel-samsung-ld9040.c | 40 ++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-samsung-ld9040.c b/drivers/gpu/drm/panel/panel-samsung-ld9040.c
index 7fd9444b42c5..b4f87d6244cb 100644
--- a/drivers/gpu/drm/panel/panel-samsung-ld9040.c
+++ b/drivers/gpu/drm/panel/panel-samsung-ld9040.c
@@ -8,6 +8,7 @@
  * Andrzej Hajda <a.hajda@samsung.com>
 */
 
+#include <linux/backlight.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/module.h>
@@ -311,8 +312,40 @@ static int ld9040_parse_dt(struct ld9040 *ctx)
 	return 0;
 }
 
+static int ld9040_bl_update_status(struct backlight_device *dev)
+{
+	struct ld9040 *ctx = dev_get_drvdata(&dev->dev);
+
+	ctx->brightness = dev->props.brightness;
+	ld9040_brightness_set(ctx);
+
+	return 0;
+}
+
+static int ld9040_bl_get_intensity(struct backlight_device *dev)
+{
+	if (dev->props.fb_blank == FB_BLANK_UNBLANK &&
+			dev->props.power == FB_BLANK_UNBLANK)
+		return dev->props.brightness;
+
+	return 0;
+}
+
+static const struct backlight_ops ld9040_bl_ops = {
+	.get_brightness = ld9040_bl_get_intensity,
+	.update_status  = ld9040_bl_update_status,
+};
+
+static const struct backlight_properties ld9040_bl_props = {
+	.type = BACKLIGHT_RAW,
+	.scale = BACKLIGHT_SCALE_NON_LINEAR,
+	.max_brightness = ARRAY_SIZE(ld9040_gammas) - 1,
+	.brightness = ARRAY_SIZE(ld9040_gammas) - 1,
+};
+
 static int ld9040_probe(struct spi_device *spi)
 {
+	struct backlight_device *bldev;
 	struct device *dev = &spi->dev;
 	struct ld9040 *ctx;
 	int ret;
@@ -354,6 +387,13 @@ static int ld9040_probe(struct spi_device *spi)
 	drm_panel_init(&ctx->panel, dev, &ld9040_drm_funcs,
 		       DRM_MODE_CONNECTOR_DPI);
 
+
+	bldev = devm_backlight_device_register(dev, dev_name(dev), dev,
+					       ctx, &ld9040_bl_ops,
+					       &ld9040_bl_props);
+	if (IS_ERR(bldev))
+		return PTR_ERR(bldev);
+
 	drm_panel_add(&ctx->panel);
 
 	return 0;
-- 
2.40.1
RE: [PATCH 2/3] drm/panel: ld9040: Register a backlight device
Posted by 대인기/Tizen Platform Lab(SR)/삼성전자 2 years, 7 months ago 
Hi,

> -----Original Message-----
> From: dri-devel <dri-devel-bounces@lists.freedesktop.org> On Behalf Of
> Paul Cercueil
> Sent: Tuesday, July 4, 2023 6:47 AM
> To: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>; Rob Herring
> <robh+dt@kernel.org>; Conor Dooley <conor+dt@kernel.org>; Alim Akhtar
> <alim.akhtar@samsung.com>; Neil Armstrong <neil.armstrong@linaro.org>; Sam
> Ravnborg <sam@ravnborg.org>
> Cc: devicetree@vger.kernel.org; linux-samsung-soc@vger.kernel.org; linux-
> kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; Paul Cercueil
> <paul@crapouillou.net>; linux-arm-kernel@lists.infradead.org
> Subject: [PATCH 2/3] drm/panel: ld9040: Register a backlight device
> 
> Register a backlight device to be able to switch between all the gamma
> levels.
> 
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> ---
>  drivers/gpu/drm/panel/panel-samsung-ld9040.c | 40 ++++++++++++++++++++
>  1 file changed, 40 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> b/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> index 7fd9444b42c5..b4f87d6244cb 100644
> --- a/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> +++ b/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> @@ -8,6 +8,7 @@
>   * Andrzej Hajda <a.hajda@samsung.com>
>  */
> 
> +#include <linux/backlight.h>
>  #include <linux/delay.h>
>  #include <linux/gpio/consumer.h>
>  #include <linux/module.h>
> @@ -311,8 +312,40 @@ static int ld9040_parse_dt(struct ld9040 *ctx)
>  	return 0;
>  }
> 
> +static int ld9040_bl_update_status(struct backlight_device *dev)
> +{
> +	struct ld9040 *ctx = dev_get_drvdata(&dev->dev);
> +
> +	ctx->brightness = dev->props.brightness;
> +	ld9040_brightness_set(ctx);
> +
> +	return 0;
> +}
> +
> +static int ld9040_bl_get_intensity(struct backlight_device *dev)
> +{
> +	if (dev->props.fb_blank == FB_BLANK_UNBLANK &&

fb_blank member is deprecated according to the description of backlight.h
file so you could drop above condition I think.

Thanks,
Inki Dae
Re: [PATCH 2/3] drm/panel: ld9040: Register a backlight device
Posted by Paul Cercueil 2 years, 7 months ago 
Hi Inki,

Le mardi 04 juillet 2023 à 08:49 +0900, 대인기/Tizen Platform Lab(SR)/삼성전자
a écrit :
> Hi,
> 
> > -----Original Message-----
> > From: dri-devel <dri-devel-bounces@lists.freedesktop.org> On Behalf
> > Of
> > Paul Cercueil
> > Sent: Tuesday, July 4, 2023 6:47 AM
> > To: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>; Rob
> > Herring
> > <robh+dt@kernel.org>; Conor Dooley <conor+dt@kernel.org>; Alim
> > Akhtar
> > <alim.akhtar@samsung.com>; Neil Armstrong
> > <neil.armstrong@linaro.org>; Sam
> > Ravnborg <sam@ravnborg.org>
> > Cc: devicetree@vger.kernel.org; linux-samsung-soc@vger.kernel.org;
> > linux-
> > kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; Paul
> > Cercueil
> > <paul@crapouillou.net>; linux-arm-kernel@lists.infradead.org
> > Subject: [PATCH 2/3] drm/panel: ld9040: Register a backlight device
> > 
> > Register a backlight device to be able to switch between all the
> > gamma
> > levels.
> > 
> > Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> > ---
> >  drivers/gpu/drm/panel/panel-samsung-ld9040.c | 40
> > ++++++++++++++++++++
> >  1 file changed, 40 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> > b/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> > index 7fd9444b42c5..b4f87d6244cb 100644
> > --- a/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> > +++ b/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> > @@ -8,6 +8,7 @@
> >   * Andrzej Hajda <a.hajda@samsung.com>
> >  */
> > 
> > +#include <linux/backlight.h>
> >  #include <linux/delay.h>
> >  #include <linux/gpio/consumer.h>
> >  #include <linux/module.h>
> > @@ -311,8 +312,40 @@ static int ld9040_parse_dt(struct ld9040 *ctx)
> >         return 0;
> >  }
> > 
> > +static int ld9040_bl_update_status(struct backlight_device *dev)
> > +{
> > +       struct ld9040 *ctx = dev_get_drvdata(&dev->dev);
> > +
> > +       ctx->brightness = dev->props.brightness;
> > +       ld9040_brightness_set(ctx);
> > +
> > +       return 0;
> > +}
> > +
> > +static int ld9040_bl_get_intensity(struct backlight_device *dev)
> > +{
> > +       if (dev->props.fb_blank == FB_BLANK_UNBLANK &&
> 
> fb_blank member is deprecated according to the description of
> backlight.h
> file so you could drop above condition I think.

Thanks. I'll send a V2.

Cheers,
-Paul
Re: [PATCH 2/3] drm/panel: ld9040: Register a backlight device
Posted by Neil Armstrong 2 years, 7 months ago 
On 03/07/2023 23:47, Paul Cercueil wrote:
> Register a backlight device to be able to switch between all the gamma
> levels.
> 
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> ---
>   drivers/gpu/drm/panel/panel-samsung-ld9040.c | 40 ++++++++++++++++++++
>   1 file changed, 40 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panel/panel-samsung-ld9040.c b/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> index 7fd9444b42c5..b4f87d6244cb 100644
> --- a/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> +++ b/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> @@ -8,6 +8,7 @@
>    * Andrzej Hajda <a.hajda@samsung.com>
>   */
>   
> +#include <linux/backlight.h>
>   #include <linux/delay.h>
>   #include <linux/gpio/consumer.h>
>   #include <linux/module.h>
> @@ -311,8 +312,40 @@ static int ld9040_parse_dt(struct ld9040 *ctx)
>   	return 0;
>   }
>   
> +static int ld9040_bl_update_status(struct backlight_device *dev)
> +{
> +	struct ld9040 *ctx = dev_get_drvdata(&dev->dev);
> +
> +	ctx->brightness = dev->props.brightness;
> +	ld9040_brightness_set(ctx);
> +
> +	return 0;
> +}
> +
> +static int ld9040_bl_get_intensity(struct backlight_device *dev)
> +{
> +	if (dev->props.fb_blank == FB_BLANK_UNBLANK &&
> +			dev->props.power == FB_BLANK_UNBLANK)
> +		return dev->props.brightness;
> +
> +	return 0;
> +}

You can totally drop the _get_brightness.

Neil

> +
> +static const struct backlight_ops ld9040_bl_ops = {
> +	.get_brightness = ld9040_bl_get_intensity,
> +	.update_status  = ld9040_bl_update_status,
> +};
> +
> +static const struct backlight_properties ld9040_bl_props = {
> +	.type = BACKLIGHT_RAW,
> +	.scale = BACKLIGHT_SCALE_NON_LINEAR,
> +	.max_brightness = ARRAY_SIZE(ld9040_gammas) - 1,
> +	.brightness = ARRAY_SIZE(ld9040_gammas) - 1,
> +};
> +
>   static int ld9040_probe(struct spi_device *spi)
>   {
> +	struct backlight_device *bldev;
>   	struct device *dev = &spi->dev;
>   	struct ld9040 *ctx;
>   	int ret;
> @@ -354,6 +387,13 @@ static int ld9040_probe(struct spi_device *spi)
>   	drm_panel_init(&ctx->panel, dev, &ld9040_drm_funcs,
>   		       DRM_MODE_CONNECTOR_DPI);
>   
> +
> +	bldev = devm_backlight_device_register(dev, dev_name(dev), dev,
> +					       ctx, &ld9040_bl_ops,
> +					       &ld9040_bl_props);
> +	if (IS_ERR(bldev))
> +		return PTR_ERR(bldev);
> +
>   	drm_panel_add(&ctx->panel);
>   
>   	return 0;
Re: [PATCH 2/3] drm/panel: ld9040: Register a backlight device
Posted by Paul Cercueil 2 years, 7 months ago 
Hi Neil,

Le mercredi 05 juillet 2023 à 15:57 +0200, Neil Armstrong a écrit :
> On 03/07/2023 23:47, Paul Cercueil wrote:
> > Register a backlight device to be able to switch between all the
> > gamma
> > levels.
> > 
> > Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> > ---
> >   drivers/gpu/drm/panel/panel-samsung-ld9040.c | 40
> > ++++++++++++++++++++
> >   1 file changed, 40 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> > b/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> > index 7fd9444b42c5..b4f87d6244cb 100644
> > --- a/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> > +++ b/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> > @@ -8,6 +8,7 @@
> >    * Andrzej Hajda <a.hajda@samsung.com>
> >   */
> >   
> > +#include <linux/backlight.h>
> >   #include <linux/delay.h>
> >   #include <linux/gpio/consumer.h>
> >   #include <linux/module.h>
> > @@ -311,8 +312,40 @@ static int ld9040_parse_dt(struct ld9040 *ctx)
> >         return 0;
> >   }
> >   
> > +static int ld9040_bl_update_status(struct backlight_device *dev)
> > +{
> > +       struct ld9040 *ctx = dev_get_drvdata(&dev->dev);
> > +
> > +       ctx->brightness = dev->props.brightness;
> > +       ld9040_brightness_set(ctx);
> > +
> > +       return 0;
> > +}
> > +
> > +static int ld9040_bl_get_intensity(struct backlight_device *dev)
> > +{
> > +       if (dev->props.fb_blank == FB_BLANK_UNBLANK &&
> > +                       dev->props.power == FB_BLANK_UNBLANK)
> > +               return dev->props.brightness;
> > +
> > +       return 0;
> > +}
> 
> You can totally drop the _get_brightness.

The current behaviour is to return 0 when the framebuffer is blanked. A
few drivers do that so I thought it was the norm; and the backlight
core doesn't do that by default (and just uses dev->props.brightness).

It is not clear to me if that's the preferred behaviour. The
"backlight_get_brightness" function in backlight.h seems to suggest
that the current behaviour is correct, unless it is not supposed to be
used in the backlight_ops.get_brightness() callback. Then in that case
some other drivers get it wrong too.

Cheers,
-Paul

> Neil
> 
> > +
> > +static const struct backlight_ops ld9040_bl_ops = {
> > +       .get_brightness = ld9040_bl_get_intensity,
> > +       .update_status  = ld9040_bl_update_status,
> > +};
> > +
> > +static const struct backlight_properties ld9040_bl_props = {
> > +       .type = BACKLIGHT_RAW,
> > +       .scale = BACKLIGHT_SCALE_NON_LINEAR,
> > +       .max_brightness = ARRAY_SIZE(ld9040_gammas) - 1,
> > +       .brightness = ARRAY_SIZE(ld9040_gammas) - 1,
> > +};
> > +
> >   static int ld9040_probe(struct spi_device *spi)
> >   {
> > +       struct backlight_device *bldev;
> >         struct device *dev = &spi->dev;
> >         struct ld9040 *ctx;
> >         int ret;
> > @@ -354,6 +387,13 @@ static int ld9040_probe(struct spi_device
> > *spi)
> >         drm_panel_init(&ctx->panel, dev, &ld9040_drm_funcs,
> >                        DRM_MODE_CONNECTOR_DPI);
> >   
> > +
> > +       bldev = devm_backlight_device_register(dev, dev_name(dev),
> > dev,
> > +                                              ctx, &ld9040_bl_ops,
> > +                                              &ld9040_bl_props);
> > +       if (IS_ERR(bldev))
> > +               return PTR_ERR(bldev);
> > +
> >         drm_panel_add(&ctx->panel);
> >   
> >         return 0;
>
Re: [PATCH 2/3] drm/panel: ld9040: Register a backlight device
Posted by Sam Ravnborg 2 years, 7 months ago 
Hi Paul,

On Wed, Jul 05, 2023 at 04:38:05PM +0200, Paul Cercueil wrote:
> Hi Neil,
> 
> Le mercredi 05 juillet 2023 à 15:57 +0200, Neil Armstrong a écrit :
> > On 03/07/2023 23:47, Paul Cercueil wrote:
> > > Register a backlight device to be able to switch between all the
> > > gamma
> > > levels.
> > > 
> > > Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> > > ---
> > >   drivers/gpu/drm/panel/panel-samsung-ld9040.c | 40
> > > ++++++++++++++++++++
> > >   1 file changed, 40 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> > > b/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> > > index 7fd9444b42c5..b4f87d6244cb 100644
> > > --- a/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> > > +++ b/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> > > @@ -8,6 +8,7 @@
> > >    * Andrzej Hajda <a.hajda@samsung.com>
> > >   */
> > >   
> > > +#include <linux/backlight.h>
> > >   #include <linux/delay.h>
> > >   #include <linux/gpio/consumer.h>
> > >   #include <linux/module.h>
> > > @@ -311,8 +312,40 @@ static int ld9040_parse_dt(struct ld9040 *ctx)
> > >         return 0;
> > >   }
> > >   
> > > +static int ld9040_bl_update_status(struct backlight_device *dev)
> > > +{
> > > +       struct ld9040 *ctx = dev_get_drvdata(&dev->dev);
> > > +
> > > +       ctx->brightness = dev->props.brightness;
Use backlight_get_brightness(dev);

> > > +       ld9040_brightness_set(ctx);
> > > +
> > > +       return 0;
> > > +}
> > > +
> > > +static int ld9040_bl_get_intensity(struct backlight_device *dev)
> > > +{
> > > +       if (dev->props.fb_blank == FB_BLANK_UNBLANK &&
> > > +                       dev->props.power == FB_BLANK_UNBLANK)
> > > +               return dev->props.brightness;
> > > +
> > > +       return 0;
> > > +}
> > 
> > You can totally drop the _get_brightness.
> 
> The current behaviour is to return 0 when the framebuffer is blanked. A
> few drivers do that so I thought it was the norm; and the backlight
> core doesn't do that by default (and just uses dev->props.brightness).
> 
> It is not clear to me if that's the preferred behaviour. The
> "backlight_get_brightness" function in backlight.h seems to suggest
> that the current behaviour is correct, unless it is not supposed to be
> used in the backlight_ops.get_brightness() callback. Then in that case
> some other drivers get it wrong too.
Several drivers get it wrong.
You are supposed to provide get_brightness only when you read back a
value from the HW, which is not the case here so just drop it is the
right choice.

	Sam
Re: [PATCH 2/3] drm/panel: ld9040: Register a backlight device
Posted by Sam Ravnborg 2 years, 7 months ago 
Hi Paul,

On Mon, Jul 03, 2023 at 11:47:14PM +0200, Paul Cercueil wrote:
> Register a backlight device to be able to switch between all the gamma
> levels.
> 
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> ---
>  drivers/gpu/drm/panel/panel-samsung-ld9040.c | 40 ++++++++++++++++++++
>  1 file changed, 40 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panel/panel-samsung-ld9040.c b/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> index 7fd9444b42c5..b4f87d6244cb 100644
> --- a/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> +++ b/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> @@ -8,6 +8,7 @@
>   * Andrzej Hajda <a.hajda@samsung.com>
>  */
>  
> +#include <linux/backlight.h>
>  #include <linux/delay.h>
>  #include <linux/gpio/consumer.h>
>  #include <linux/module.h>
> @@ -311,8 +312,40 @@ static int ld9040_parse_dt(struct ld9040 *ctx)
>  	return 0;
>  }
>  
> +static int ld9040_bl_update_status(struct backlight_device *dev)
> +{
> +	struct ld9040 *ctx = dev_get_drvdata(&dev->dev);
There is also the helper bl_get_data() - that do the same.

	Sam

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