[Intel-gfx] [MIPI CABC 2/2] drm/i915: CABC support for backlight control

Jani Nikula jani.nikula at intel.com
Wed Nov 25 04:26:36 PST 2015


On Mon, 16 Nov 2015, Deepak M <m.deepak at intel.com> wrote:
> In CABC (Content Adaptive Brightness Control) content grey level
> scale can be increased while simultaneously decreasing
> brightness of the backlight to achieve same perceived brightness.
>
> The CABC is not standardized and panel vendors are free to follow
> their implementation. The CABC implementaion here assumes that the
> panels use standard SW register for control.
>
> In this design there will be no PWM signal from the SoC and DCS
> commands are sent to enable and control the backlight brightness.

I'd like you to move the DSI DCS backlight stuff from intel_panel.c to a
new file, say, intel_dsi_dcs_backlight.c, similar to what I told Yetunde
to do with DP DPCD backlight [1].

[1] http://patchwork.freedesktop.org/patch/msgid/1447698547-9027-1-git-send-email-yetundex.adebisi@intel.com

> Cc: Jani Nikula <jani.nikula at intel.com>
> Cc: Daniel Vetter <daniel.vetter at intel.com>
> Cc: Yetunde Adebisi <yetundex.adebisi at intel.com>
> Signed-off-by: Deepak M <m.deepak at intel.com>
> ---
> Addressed the review comments from Jani which were mentioned in
> the below patch
> http://lists.freedesktop.org/archives/intel-gfx/2015-September/075819.html
>
> Went with the name CABC because the commands which are used
> here are mainly for CABC and many of the panels have the same
> commands for the CABC operation. For the cases where PWM is
> directly from panel PWM, DCS commands may be different and
> may have to add new functions to support it.
>
>  drivers/gpu/drm/i915/intel_dsi.c   |  14 +++-
>  drivers/gpu/drm/i915/intel_dsi.h   |  24 ++++++
>  drivers/gpu/drm/i915/intel_panel.c | 145 +++++++++++++++++++++++++++++++++++--
>  3 files changed, 177 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
> index 170ae6f..5d1ba35 100644
> --- a/drivers/gpu/drm/i915/intel_dsi.c
> +++ b/drivers/gpu/drm/i915/intel_dsi.c
> @@ -1175,8 +1175,20 @@ void intel_dsi_init(struct drm_device *dev)
>  		intel_dsi->ports = (1 << PORT_C);
>  	}
>  
> -	if (dev_priv->vbt.dsi.config->dual_link)
> +	if (dev_priv->vbt.dsi.config->dual_link) {
>  		intel_dsi->ports = ((1 << PORT_A) | (1 << PORT_C));
> +		switch (dev_priv->vbt.dsi.config->dl_cabc_port) {
> +		case CABC_PORT_A:
> +			intel_dsi->bkl_dcs_ports = (1 << PORT_A);
> +		case CABC_PORT_C:
> +			intel_dsi->bkl_dcs_ports = (1 << PORT_C);
> +		case CABC_PORT_A_AND_C:
> +			intel_dsi->bkl_dcs_ports = intel_dsi->ports;
> +		default:
> +			DRM_ERROR("Unknown MIPI ports for sending DCS\n");

"break;" is useful in making the switch case do what you want.

> +		}
> +	} else
> +		intel_dsi->bkl_dcs_ports = intel_dsi->ports;
>  
>  	/* Create a DSI host (and a device) for each port. */
>  	for_each_dsi_port(port, intel_dsi->ports) {
> diff --git a/drivers/gpu/drm/i915/intel_dsi.h b/drivers/gpu/drm/i915/intel_dsi.h
> index 4fde83b..4bcee40 100644
> --- a/drivers/gpu/drm/i915/intel_dsi.h
> +++ b/drivers/gpu/drm/i915/intel_dsi.h
> @@ -34,6 +34,30 @@
>  #define DSI_DUAL_LINK_FRONT_BACK	1
>  #define DSI_DUAL_LINK_PIXEL_ALT		2
>  
> +#define CABC_OFF			(0 << 0)
> +#define CABC_USER_INTERFACE_IMAGE	(1 << 0)
> +#define CABC_STILL_PICTURE		(2 << 0)
> +#define CABC_VIDEO_MODE			(3 << 0)
> +
> +#define CABC_BACKLIGHT			(1 << 2)
> +#define CABC_DIMMING_DISPLAY		(1 << 3)
> +#define CABC_BCTRL			(1 << 5)
> +
> +#define CABC_PORT_A			0x00
> +#define CABC_PORT_C			0x01
> +#define CABC_PORT_A_AND_C		0x02
> +
> +#define CABC_MAX_VALUE			0xFF
> +
> +#define MIPI_DCS_CABC_LEVEL_RD		0x52
> +#define MIPI_DCS_CABC_MIN_BRIGHTNESS_RD	0x5F
> +#define MIPI_DCS_CABC_CONTROL_RD	0x56
> +#define MIPI_DCS_CABC_CONTROL_BRIGHT_RD	0x54
> +#define MIPI_DCS_CABC_LEVEL_WR		0x51
> +#define MIPI_DCS_CABC_MIN_BRIGHTNESS_WR	0x5E
> +#define MIPI_DCS_CABC_CONTROL_WR	0x55
> +#define MIPI_DCS_CABC_CONTROL_BRIGHT_WR	0x53
> +

Put these in the new .c file. The rest of the code shouldn't need to know.

>  struct intel_dsi_host;
>  
>  struct intel_dsi {
> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> index a24df35..085d9a6 100644
> --- a/drivers/gpu/drm/i915/intel_panel.c
> +++ b/drivers/gpu/drm/i915/intel_panel.c
> @@ -34,6 +34,7 @@
>  #include <linux/moduleparam.h>
>  #include <linux/pwm.h>
>  #include "intel_drv.h"
> +#include "intel_dsi.h"
>  
>  #define CRC_PMIC_PWM_PERIOD_NS	21333
>  
> @@ -533,6 +534,30 @@ static u32 vlv_get_backlight(struct intel_connector *connector)
>  	return _vlv_get_backlight(dev, pipe);
>  }
>  
> +static u32 cabc_get_backlight(struct intel_connector *connector)
> +{
> +	struct intel_dsi *intel_dsi = NULL;
> +	struct intel_encoder *encoder = NULL;
> +	struct mipi_dsi_device *dsi_device;
> +	u8 data[2] = {0};
> +	enum port port;
> +
> +	encoder = connector->encoder;
> +	if (encoder->type == INTEL_OUTPUT_DSI)
> +		intel_dsi = enc_to_intel_dsi(&encoder->base);
> +	else {
> +		DRM_ERROR("Use DSI encoder for CABC\n");
> +		return -EINVAL;
> +	}

You need to check this once when you setup the CABC backlight, and not
afterwards. In the function that sets up the CABC backlight hooks, not
the setup hook itself.

> +
> +	for_each_dsi_port(port, intel_dsi->bkl_dcs_ports) {
> +		dsi_device = intel_dsi->dsi_hosts[port]->device;
> +		mipi_dsi_dcs_read(dsi_device, MIPI_DCS_CABC_LEVEL_RD, data, 2);
> +	}
> +
> +	return data[1];
> +}
> +
>  static u32 bxt_get_backlight(struct intel_connector *connector)
>  {
>  	struct drm_device *dev = connector->base.dev;
> @@ -631,6 +656,30 @@ static void vlv_set_backlight(struct intel_connector *connector, u32 level)
>  	I915_WRITE(VLV_BLC_PWM_CTL(pipe), tmp | level);
>  }
>  
> +static void cabc_set_backlight(struct intel_connector *connector, u32 level)
> +{
> +	struct intel_dsi *intel_dsi = NULL;
> +	struct intel_encoder *encoder = NULL;
> +	struct mipi_dsi_device *dsi_device;
> +	u8 data[2] = {0};
> +	enum port port;
> +
> +	encoder = connector->encoder;
> +	if (encoder->type == INTEL_OUTPUT_DSI)
> +		intel_dsi = enc_to_intel_dsi(&encoder->base);
> +	else {
> +		DRM_ERROR("Use DSI encoder for CABC\n");
> +		return;
> +	}

Same as above.

> +
> +	for_each_dsi_port(port, intel_dsi->bkl_dcs_ports) {
> +		dsi_device = intel_dsi->dsi_hosts[port]->device;
> +		data[1] = level;
> +		data[0] = MIPI_DCS_CABC_LEVEL_WR;
> +		mipi_dsi_dcs_write_buffer(dsi_device, data, 2);
> +	}
> +}
> +
>  static void bxt_set_backlight(struct intel_connector *connector, u32 level)
>  {
>  	struct drm_device *dev = connector->base.dev;
> @@ -798,6 +847,34 @@ static void vlv_disable_backlight(struct intel_connector *connector)
>  	I915_WRITE(VLV_BLC_PWM_CTL2(pipe), tmp & ~BLM_PWM_ENABLE);
>  }
>  
> +static void cabc_disable_backlight(struct intel_connector *connector)
> +{
> +	struct intel_dsi *intel_dsi = NULL;
> +	struct intel_encoder *encoder = NULL;
> +	struct mipi_dsi_device *dsi_device;
> +	enum port port;
> +	u8 data[2] = {0};
> +
> +	encoder = connector->encoder;
> +	if (encoder->type == INTEL_OUTPUT_DSI)
> +		intel_dsi = enc_to_intel_dsi(&encoder->base);
> +	else {
> +		DRM_ERROR("Use DSI encoder for CABC\n");
> +		return;
> +	}

Same as above.

> +
> +	intel_panel_actually_set_backlight(connector, 0);
> +
> +	for_each_dsi_port(port, intel_dsi->bkl_dcs_ports) {
> +		dsi_device = intel_dsi->dsi_hosts[port]->device;
> +		data[1] = CABC_OFF;
> +		data[0] = MIPI_DCS_CABC_CONTROL_WR;
> +		mipi_dsi_dcs_write_buffer(dsi_device, data, 2);
> +		data[0] = MIPI_DCS_CABC_CONTROL_BRIGHT_WR;
> +		mipi_dsi_dcs_write_buffer(dsi_device, data, 2);
> +	}
> +}
> +
>  static void bxt_disable_backlight(struct intel_connector *connector)
>  {
>  	struct drm_device *dev = connector->base.dev;
> @@ -1133,6 +1210,36 @@ void intel_panel_enable_backlight(struct intel_connector *connector)
>  	mutex_unlock(&dev_priv->backlight_lock);
>  }
>  
> +static void cabc_enable_backlight(struct intel_connector *connector)
> +{
> +	struct intel_dsi *intel_dsi = NULL;
> +	struct intel_encoder *encoder = NULL;
> +	struct intel_panel *panel = &connector->panel;
> +	struct mipi_dsi_device *dsi_device;
> +	enum port port;
> +	u8 data[2] = {0};
> +
> +	encoder = connector->encoder;
> +	if (encoder->type == INTEL_OUTPUT_DSI)
> +		intel_dsi = enc_to_intel_dsi(&encoder->base);
> +	else {
> +		DRM_ERROR("Use DSI encoder for the CABC\n");
> +		return;
> +	}


Same as above.

> +
> +	for_each_dsi_port(port, intel_dsi->bkl_dcs_ports) {
> +		dsi_device = intel_dsi->dsi_hosts[port]->device;
> +		data[0] = MIPI_DCS_CABC_CONTROL_BRIGHT_WR;
> +		data[1] = CABC_BACKLIGHT | CABC_DIMMING_DISPLAY | CABC_BCTRL;
> +		mipi_dsi_dcs_write_buffer(dsi_device, data, 2);
> +		data[0] = MIPI_DCS_CABC_CONTROL_WR;
> +		data[1] = CABC_STILL_PICTURE;
> +		mipi_dsi_dcs_write_buffer(dsi_device, data, 2);
> +	}
> +
> +	intel_panel_actually_set_backlight(connector, panel->backlight.level);
> +}
> +
>  #if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
>  static int intel_backlight_device_update_status(struct backlight_device *bd)
>  {
> @@ -1601,6 +1708,26 @@ static int vlv_setup_backlight(struct intel_connector *connector, enum pipe pipe
>  	return 0;
>  }
>  
> +static int cabc_setup_backlight(struct intel_connector *connector,
> +		enum pipe unused)
> +{
> +	struct drm_device *dev = connector->base.dev;
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	struct intel_panel *panel = &connector->panel;
> +
> +	if (dev_priv->vbt.backlight.present)
> +		panel->backlight.present = true;
> +	else {
> +		DRM_ERROR("no backlight present per VBT\n");
> +		return 0;
> +	}

Same as above.

> +
> +	panel->backlight.max = CABC_MAX_VALUE;
> +	panel->backlight.level = CABC_MAX_VALUE;
> +
> +	return 0;
> +}
> +
>  static int
>  bxt_setup_backlight(struct intel_connector *connector, enum pipe unused)
>  {
> @@ -1745,11 +1872,19 @@ intel_panel_init_backlight_funcs(struct intel_panel *panel)
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  
>  	if (IS_BROXTON(dev)) {
> -		panel->backlight.setup = bxt_setup_backlight;
> -		panel->backlight.enable = bxt_enable_backlight;
> -		panel->backlight.disable = bxt_disable_backlight;
> -		panel->backlight.set = bxt_set_backlight;
> -		panel->backlight.get = bxt_get_backlight;
> +		if (dev_priv->vbt.dsi.config->cabc_supported) {
> +			panel->backlight.setup = cabc_setup_backlight;
> +			panel->backlight.enable = cabc_enable_backlight;
> +			panel->backlight.disable = cabc_disable_backlight;
> +			panel->backlight.set = cabc_set_backlight;
> +			panel->backlight.get = cabc_get_backlight;
> +		} else {
> +			panel->backlight.setup = bxt_setup_backlight;
> +			panel->backlight.enable = bxt_enable_backlight;
> +			panel->backlight.disable = bxt_disable_backlight;
> +			panel->backlight.set = bxt_set_backlight;
> +			panel->backlight.get = bxt_get_backlight;
> +		}

Why is this Broxton specific? It's DSI specific, so please do this
similar to what I told Yetunde to do with DP AUX backlight.


>  	} else if (HAS_PCH_LPT(dev) || HAS_PCH_SPT(dev)) {
>  		panel->backlight.setup = lpt_setup_backlight;
>  		panel->backlight.enable = lpt_enable_backlight;

-- 
Jani Nikula, Intel Open Source Technology Center


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