[PATCH 1/2] drm/dsi: Implement set tear scanline

[PATCH 1/2] drm/dsi: Implement set tear scanline

[Vinay Simha BN]

Provide a small convenience wrapper that transmits
ia set_tear_scanline command as suggested by
Thierry Reding.

Also includes small build fixes from Sumit Semwal.

Cc: Archit Taneja <archit.taneja@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Vinay Simha BN <simhavcs@gmail.com>
---
 drivers/gpu/drm/drm_mipi_dsi.c | 23 +++++++++++++++++++++++
 include/drm/drm_mipi_dsi.h     |  2 ++
 2 files changed, 25 insertions(+)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index f5d8083..2f0b85c 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -983,6 +983,29 @@ int mipi_dsi_dcs_set_tear_on(struct mipi_dsi_device *dsi,
 EXPORT_SYMBOL(mipi_dsi_dcs_set_tear_on);
 
 /**
+ * mipi_dsi_set_tear_scanline() - turn on the display module's Tearing Effect
+ * output signal on the TE signal line when display module reaches line N
+ * defined by STS[n:0].
+ * @dsi: DSI peripheral device
+ * @param1: STS[10:8]
+ * @param2: STS[7:0]
+ * Return: 0 on success or a negative error code on failure
+ */
+int mipi_dsi_set_tear_scanline(struct mipi_dsi_device *dsi,
+			       u8 param1, u8 param2)
+{
+	u8 payload[3] = { MIPI_DCS_SET_TEAR_SCANLINE, param1, param2};
+	ssize_t err;
+
+	err = mipi_dsi_generic_write(dsi, &payload, sizeof(payload));
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+EXPORT_SYMBOL(mipi_dsi_set_tear_scanline);
+
+/**
  * mipi_dsi_dcs_set_pixel_format() - sets the pixel format for the RGB image
  *    data used by the interface
  * @dsi: DSI peripheral device
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index 7a9840f..2788dbe 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -263,6 +263,8 @@ int mipi_dsi_dcs_set_column_address(struct mipi_dsi_device *dsi, u16 start,
 				    u16 end);
 int mipi_dsi_dcs_set_page_address(struct mipi_dsi_device *dsi, u16 start,
 				  u16 end);
+int mipi_dsi_set_tear_scanline(struct mipi_dsi_device *dsi, u8 param1,
+			       u8 param2);
 int mipi_dsi_dcs_set_tear_off(struct mipi_dsi_device *dsi);
 int mipi_dsi_dcs_set_tear_on(struct mipi_dsi_device *dsi,
 			     enum mipi_dsi_dcs_tear_mode mode);
-- 
1.9.1

[PATCH 2/2] drm/dsi: Implement dcs backlight brightness

[Vinay Simha BN]

Provide a small convenience wrapper that set/get the
backlight brightness control and creates the backlight
device for the panel interface

Cc: John Stultz <john.stultz@linaro.org>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Archit Taneja <archit.taneja@gmail.com>
Cc: Rob Clark <robdclark@gmail.com>
Signed-off-by: Vinay Simha BN <simhavcs@gmail.com>

--
v1:
 *tested in nexus7 2nd gen.
---
 drivers/gpu/drm/drm_mipi_dsi.c | 63 ++++++++++++++++++++++++++++++++++++++++++
 include/drm/drm_mipi_dsi.h     |  3 ++
 2 files changed, 66 insertions(+)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index 2f0b85c..ac4521e 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -1026,6 +1026,69 @@ int mipi_dsi_dcs_set_pixel_format(struct mipi_dsi_device *dsi, u8 format)
 }
 EXPORT_SYMBOL(mipi_dsi_dcs_set_pixel_format);
 
+static int dsi_dcs_bl_get_brightness(struct backlight_device *bl)
+{
+	struct mipi_dsi_device *dsi = bl_get_data(bl);
+	int ret;
+	u8 brightness;
+
+	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
+
+	ret = mipi_dsi_dcs_read(dsi, MIPI_DCS_GET_DISPLAY_BRIGHTNESS,
+				&brightness, sizeof(brightness));
+	if (ret < 0)
+		return ret;
+
+	dsi->mode_flags |= MIPI_DSI_MODE_LPM;
+
+	return brightness;
+}
+
+static int dsi_dcs_bl_update_status(struct backlight_device *bl)
+{
+	struct mipi_dsi_device *dsi = bl_get_data(bl);
+	int ret;
+	u8 brightness = bl->props.brightness;
+
+	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
+
+	ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
+				 &brightness, sizeof(brightness));
+	if (ret < 0)
+		return ret;
+
+	dsi->mode_flags |= MIPI_DSI_MODE_LPM;
+
+	return 0;
+}
+
+static const struct backlight_ops dsi_bl_ops = {
+	.update_status = dsi_dcs_bl_update_status,
+	.get_brightness = dsi_dcs_bl_get_brightness,
+};
+
+/**
+ * drm_panel_create_dsi_backlight() - creates the backlight device for the panel
+ * @dsi: DSI peripheral device
+ *
+ * @return a struct backlight on success, or an ERR_PTR on error
+ */
+struct backlight_device
+		*drm_panel_create_dsi_backlight(struct mipi_dsi_device *dsi)
+{
+	struct device *dev = &dsi->dev;
+	struct backlight_properties props;
+
+	memset(&props, 0, sizeof(props));
+	props.type = BACKLIGHT_RAW;
+	props.brightness = 255;
+	props.max_brightness = 255;
+
+	return devm_backlight_device_register(dev, dev_name(dev), dev, dsi,
+					      &dsi_bl_ops, &props);
+}
+EXPORT_SYMBOL(drm_panel_create_dsi_backlight);
+
 static int mipi_dsi_drv_probe(struct device *dev)
 {
 	struct mipi_dsi_driver *drv = to_mipi_dsi_driver(dev->driver);
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index 2788dbe..9dd6a97 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -12,6 +12,7 @@
 #ifndef __DRM_MIPI_DSI_H__
 #define __DRM_MIPI_DSI_H__
 
+#include <linux/backlight.h>
 #include <linux/device.h>
 
 struct mipi_dsi_host;
@@ -269,6 +270,8 @@ int mipi_dsi_dcs_set_tear_off(struct mipi_dsi_device *dsi);
 int mipi_dsi_dcs_set_tear_on(struct mipi_dsi_device *dsi,
 			     enum mipi_dsi_dcs_tear_mode mode);
 int mipi_dsi_dcs_set_pixel_format(struct mipi_dsi_device *dsi, u8 format);
+struct backlight_device
+	*drm_panel_create_dsi_backlight(struct mipi_dsi_device *dsi);
 
 /**
  * struct mipi_dsi_driver - DSI driver
-- 
1.9.1

Re: [PATCH 1/2] drm/dsi: Implement set tear scanline

[Jani Nikula]

On Thu, 02 Jun 2016, Vinay Simha BN <simhavcs@gmail.com> wrote:
> Provide a small convenience wrapper that transmits
> ia set_tear_scanline command as suggested by
> Thierry Reding.
>
> Also includes small build fixes from Sumit Semwal.
>
> Cc: Archit Taneja <archit.taneja@gmail.com>
> Cc: John Stultz <john.stultz@linaro.org>
> Cc: Thierry Reding <thierry.reding@gmail.com>
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Signed-off-by: Vinay Simha BN <simhavcs@gmail.com>
> ---
>  drivers/gpu/drm/drm_mipi_dsi.c | 23 +++++++++++++++++++++++
>  include/drm/drm_mipi_dsi.h     |  2 ++
>  2 files changed, 25 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
> index f5d8083..2f0b85c 100644
> --- a/drivers/gpu/drm/drm_mipi_dsi.c
> +++ b/drivers/gpu/drm/drm_mipi_dsi.c
> @@ -983,6 +983,29 @@ int mipi_dsi_dcs_set_tear_on(struct mipi_dsi_device *dsi,
>  EXPORT_SYMBOL(mipi_dsi_dcs_set_tear_on);
>  
>  /**
> + * mipi_dsi_set_tear_scanline() - turn on the display module's Tearing Effect
> + * output signal on the TE signal line when display module reaches line N
> + * defined by STS[n:0].
> + * @dsi: DSI peripheral device
> + * @param1: STS[10:8]
> + * @param2: STS[7:0]
> + * Return: 0 on success or a negative error code on failure
> + */
> +int mipi_dsi_set_tear_scanline(struct mipi_dsi_device *dsi,
> +			       u8 param1, u8 param2)

If you're making a helper, please make using it easy and have *one*
scanline parameter.

BR,
Jani.

> +{
> +	u8 payload[3] = { MIPI_DCS_SET_TEAR_SCANLINE, param1, param2};
> +	ssize_t err;
> +
> +	err = mipi_dsi_generic_write(dsi, &payload, sizeof(payload));
> +	if (err < 0)
> +		return err;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(mipi_dsi_set_tear_scanline);
> +
> +/**
>   * mipi_dsi_dcs_set_pixel_format() - sets the pixel format for the RGB image
>   *    data used by the interface
>   * @dsi: DSI peripheral device
> diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
> index 7a9840f..2788dbe 100644
> --- a/include/drm/drm_mipi_dsi.h
> +++ b/include/drm/drm_mipi_dsi.h
> @@ -263,6 +263,8 @@ int mipi_dsi_dcs_set_column_address(struct mipi_dsi_device *dsi, u16 start,
>  				    u16 end);
>  int mipi_dsi_dcs_set_page_address(struct mipi_dsi_device *dsi, u16 start,
>  				  u16 end);
> +int mipi_dsi_set_tear_scanline(struct mipi_dsi_device *dsi, u8 param1,
> +			       u8 param2);
>  int mipi_dsi_dcs_set_tear_off(struct mipi_dsi_device *dsi);
>  int mipi_dsi_dcs_set_tear_on(struct mipi_dsi_device *dsi,
>  			     enum mipi_dsi_dcs_tear_mode mode);

-- 
Jani Nikula, Intel Open Source Technology Center

Re: [PATCH 2/2] drm/dsi: Implement dcs backlight brightness

[Jani Nikula]

On Thu, 02 Jun 2016, Vinay Simha BN <simhavcs@gmail.com> wrote:
> Provide a small convenience wrapper that set/get the
> backlight brightness control and creates the backlight
> device for the panel interface

To be pedantic, we should downplay "backlight" in the DSI DCS brightness
control... there need not be a backlight, at all, for brightness control
(see AMOLED).

> Cc: John Stultz <john.stultz@linaro.org>
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Cc: Archit Taneja <archit.taneja@gmail.com>
> Cc: Rob Clark <robdclark@gmail.com>
> Signed-off-by: Vinay Simha BN <simhavcs@gmail.com>
>
> --
> v1:
>  *tested in nexus7 2nd gen.
> ---
>  drivers/gpu/drm/drm_mipi_dsi.c | 63 ++++++++++++++++++++++++++++++++++++++++++
>  include/drm/drm_mipi_dsi.h     |  3 ++
>  2 files changed, 66 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
> index 2f0b85c..ac4521e 100644
> --- a/drivers/gpu/drm/drm_mipi_dsi.c
> +++ b/drivers/gpu/drm/drm_mipi_dsi.c
> @@ -1026,6 +1026,69 @@ int mipi_dsi_dcs_set_pixel_format(struct mipi_dsi_device *dsi, u8 format)
>  }
>  EXPORT_SYMBOL(mipi_dsi_dcs_set_pixel_format);
>  
> +static int dsi_dcs_bl_get_brightness(struct backlight_device *bl)

I'd rather see convenience helpers that are not tied to struct
backlight_device. You can add a one-line wrapper on top that takes
struct backlight_device pointer.

While at it, please name the helpers according to the DCS command.

> +{
> +	struct mipi_dsi_device *dsi = bl_get_data(bl);
> +	int ret;
> +	u8 brightness;
> +
> +	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
> +
> +	ret = mipi_dsi_dcs_read(dsi, MIPI_DCS_GET_DISPLAY_BRIGHTNESS,
> +				&brightness, sizeof(brightness));
> +	if (ret < 0)
> +		return ret;
> +
> +	dsi->mode_flags |= MIPI_DSI_MODE_LPM;
> +
> +	return brightness;
> +}
> +
> +static int dsi_dcs_bl_update_status(struct backlight_device *bl)
> +{
> +	struct mipi_dsi_device *dsi = bl_get_data(bl);
> +	int ret;
> +	u8 brightness = bl->props.brightness;
> +
> +	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
> +
> +	ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
> +				 &brightness, sizeof(brightness));
> +	if (ret < 0)
> +		return ret;
> +
> +	dsi->mode_flags |= MIPI_DSI_MODE_LPM;
> +
> +	return 0;
> +}
> +
> +static const struct backlight_ops dsi_bl_ops = {
> +	.update_status = dsi_dcs_bl_update_status,
> +	.get_brightness = dsi_dcs_bl_get_brightness,
> +};
> +
> +/**
> + * drm_panel_create_dsi_backlight() - creates the backlight device for the panel
> + * @dsi: DSI peripheral device
> + *
> + * @return a struct backlight on success, or an ERR_PTR on error
> + */
> +struct backlight_device
> +		*drm_panel_create_dsi_backlight(struct mipi_dsi_device *dsi)
> +{
> +	struct device *dev = &dsi->dev;
> +	struct backlight_properties props;
> +
> +	memset(&props, 0, sizeof(props));
> +	props.type = BACKLIGHT_RAW;
> +	props.brightness = 255;
> +	props.max_brightness = 255;

The DCS spec says the max is either 0xff or 0xffff depending on the
implementation... this obviously affects the helpers as well.

And how about the backlight bits in write_control_display? I just fear
this is a simplistic view of brightness control on DSI, and this will
grow hairy over time. I think I'd rather see generic DSI DCS brightness
*helpers* in this file, and then *perhaps* a separate file for
brightness control in general.

BR,
Jani.

> +
> +	return devm_backlight_device_register(dev, dev_name(dev), dev, dsi,
> +					      &dsi_bl_ops, &props);
> +}
> +EXPORT_SYMBOL(drm_panel_create_dsi_backlight);
> +
>  static int mipi_dsi_drv_probe(struct device *dev)
>  {
>  	struct mipi_dsi_driver *drv = to_mipi_dsi_driver(dev->driver);
> diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
> index 2788dbe..9dd6a97 100644
> --- a/include/drm/drm_mipi_dsi.h
> +++ b/include/drm/drm_mipi_dsi.h
> @@ -12,6 +12,7 @@
>  #ifndef __DRM_MIPI_DSI_H__
>  #define __DRM_MIPI_DSI_H__
>  
> +#include <linux/backlight.h>
>  #include <linux/device.h>
>  
>  struct mipi_dsi_host;
> @@ -269,6 +270,8 @@ int mipi_dsi_dcs_set_tear_off(struct mipi_dsi_device *dsi);
>  int mipi_dsi_dcs_set_tear_on(struct mipi_dsi_device *dsi,
>  			     enum mipi_dsi_dcs_tear_mode mode);
>  int mipi_dsi_dcs_set_pixel_format(struct mipi_dsi_device *dsi, u8 format);
> +struct backlight_device
> +	*drm_panel_create_dsi_backlight(struct mipi_dsi_device *dsi);
>  
>  /**
>   * struct mipi_dsi_driver - DSI driver

-- 
Jani Nikula, Intel Open Source Technology Center

Re: [PATCH 2/2] drm/dsi: Implement dcs backlight brightness

[Vinay Simha]

On Mon, Jun 6, 2016 at 1:07 PM, Jani Nikula <jani.nikula@linux.intel.com> wrote:
> On Thu, 02 Jun 2016, Vinay Simha BN <simhavcs@gmail.com> wrote:
>> Provide a small convenience wrapper that set/get the
>> backlight brightness control and creates the backlight
>> device for the panel interface
>
> To be pedantic, we should downplay "backlight" in the DSI DCS brightness
> control... there need not be a backlight, at all, for brightness control
> (see AMOLED).
but this jdi display and few other dsi display can be controlled by dcs commands

>
>> Cc: John Stultz <john.stultz@linaro.org>
>> Cc: Sumit Semwal <sumit.semwal@linaro.org>
>> Cc: Archit Taneja <archit.taneja@gmail.com>
>> Cc: Rob Clark <robdclark@gmail.com>
>> Signed-off-by: Vinay Simha BN <simhavcs@gmail.com>
>>
>> --
>> v1:
>>  *tested in nexus7 2nd gen.
>> ---
>>  drivers/gpu/drm/drm_mipi_dsi.c | 63 ++++++++++++++++++++++++++++++++++++++++++
>>  include/drm/drm_mipi_dsi.h     |  3 ++
>>  2 files changed, 66 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
>> index 2f0b85c..ac4521e 100644
>> --- a/drivers/gpu/drm/drm_mipi_dsi.c
>> +++ b/drivers/gpu/drm/drm_mipi_dsi.c
>> @@ -1026,6 +1026,69 @@ int mipi_dsi_dcs_set_pixel_format(struct mipi_dsi_device *dsi, u8 format)
>>  }
>>  EXPORT_SYMBOL(mipi_dsi_dcs_set_pixel_format);
>>
>> +static int dsi_dcs_bl_get_brightness(struct backlight_device *bl)
>
> I'd rather see convenience helpers that are not tied to struct
> backlight_device. You can add a one-line wrapper on top that takes
> struct backlight_device pointer.
>
i need to move the backlight_ops, backlight struct in panel driver and need to
set/get brightness in drm_mipi_dsi.c
> While at it, please name the helpers according to the DCS command.
i will changes this to in v2 version
mipi_dsi_dcs_set_brightness
mipi_dsi_dcs_get_brightness
>
>> +{
>> +     struct mipi_dsi_device *dsi = bl_get_data(bl);
>> +     int ret;
>> +     u8 brightness;
>> +
>> +     dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
>> +
>> +     ret = mipi_dsi_dcs_read(dsi, MIPI_DCS_GET_DISPLAY_BRIGHTNESS,
>> +                             &brightness, sizeof(brightness));
>> +     if (ret < 0)
>> +             return ret;
>> +
>> +     dsi->mode_flags |= MIPI_DSI_MODE_LPM;
>> +
>> +     return brightness;
>> +}
>> +
>> +static int dsi_dcs_bl_update_status(struct backlight_device *bl)
>> +{
>> +     struct mipi_dsi_device *dsi = bl_get_data(bl);
>> +     int ret;
>> +     u8 brightness = bl->props.brightness;
>> +
>> +     dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
>> +
>> +     ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
>> +                              &brightness, sizeof(brightness));
>> +     if (ret < 0)
>> +             return ret;
>> +
>> +     dsi->mode_flags |= MIPI_DSI_MODE_LPM;
>> +
>> +     return 0;
>> +}
>> +
>> +static const struct backlight_ops dsi_bl_ops = {
>> +     .update_status = dsi_dcs_bl_update_status,
>> +     .get_brightness = dsi_dcs_bl_get_brightness,
>> +};
>> +
>> +/**
>> + * drm_panel_create_dsi_backlight() - creates the backlight device for the panel
>> + * @dsi: DSI peripheral device
>> + *
>> + * @return a struct backlight on success, or an ERR_PTR on error
>> + */
>> +struct backlight_device
>> +             *drm_panel_create_dsi_backlight(struct mipi_dsi_device *dsi)
>> +{
>> +     struct device *dev = &dsi->dev;
>> +     struct backlight_properties props;
>> +
>> +     memset(&props, 0, sizeof(props));
>> +     props.type = BACKLIGHT_RAW;
>> +     props.brightness = 255;
>> +     props.max_brightness = 255;
>
> The DCS spec says the max is either 0xff or 0xffff depending on the
> implementation... this obviously affects the helpers as well.
>
> And how about the backlight bits in write_control_display? 8 bits
I just fear
> this is a simplistic view of brightness control on DSI, and this will
> grow hairy over time. I think I'd rather see generic DSI DCS brightness
> *helpers* in this file, and then *perhaps* a separate file for
> brightness control in general.
>
> BR,
> Jani.
>
>> +
>> +     return devm_backlight_device_register(dev, dev_name(dev), dev, dsi,
>> +                                           &dsi_bl_ops, &props);
>> +}
>> +EXPORT_SYMBOL(drm_panel_create_dsi_backlight);
>> +
>>  static int mipi_dsi_drv_probe(struct device *dev)
>>  {
>>       struct mipi_dsi_driver *drv = to_mipi_dsi_driver(dev->driver);
>> diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
>> index 2788dbe..9dd6a97 100644
>> --- a/include/drm/drm_mipi_dsi.h
>> +++ b/include/drm/drm_mipi_dsi.h
>> @@ -12,6 +12,7 @@
>>  #ifndef __DRM_MIPI_DSI_H__
>>  #define __DRM_MIPI_DSI_H__
>>
>> +#include <linux/backlight.h>
>>  #include <linux/device.h>
>>
>>  struct mipi_dsi_host;
>> @@ -269,6 +270,8 @@ int mipi_dsi_dcs_set_tear_off(struct mipi_dsi_device *dsi);
>>  int mipi_dsi_dcs_set_tear_on(struct mipi_dsi_device *dsi,
>>                            enum mipi_dsi_dcs_tear_mode mode);
>>  int mipi_dsi_dcs_set_pixel_format(struct mipi_dsi_device *dsi, u8 format);
>> +struct backlight_device
>> +     *drm_panel_create_dsi_backlight(struct mipi_dsi_device *dsi);
>>
>>  /**
>>   * struct mipi_dsi_driver - DSI driver
>
> --
> Jani Nikula, Intel Open Source Technology Center



-- 
Regards,

Vinay Simha.B.N.

Re: [PATCH 2/2] drm/dsi: Implement dcs backlight brightness

[Jani Nikula]

On Mon, 06 Jun 2016, Vinay Simha <simhavcs@gmail.com> wrote:
> On Mon, Jun 6, 2016 at 1:07 PM, Jani Nikula <jani.nikula@linux.intel.com> wrote:
>> On Thu, 02 Jun 2016, Vinay Simha BN <simhavcs@gmail.com> wrote:
>>> Provide a small convenience wrapper that set/get the
>>> backlight brightness control and creates the backlight
>>> device for the panel interface
>>
>> To be pedantic, we should downplay "backlight" in the DSI DCS brightness
>> control... there need not be a backlight, at all, for brightness control
>> (see AMOLED).
> but this jdi display and few other dsi display can be controlled by
> dcs commands

The point I was trying to convey was that the DSI DCS interface is
agnostic to the actual method of controlling brightness. Whether the
panel has a backlight to control brightness is a panel implementation
detail. So maybe we shouldn't have "backlight" in the interface
nomenclature either.

BR,
Jani.

-- 
Jani Nikula, Intel Open Source Technology Center