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.

CABC is supported only when the PWM source for backlight is
from the panel.

Cc: Jani Nikula <jani.nik...@intel.com>
Cc: Daniel Vetter <daniel.vet...@intel.com>
Cc: Yetunde Adebisi <yetundex.adeb...@intel.com>
Signed-off-by: Deepak M <m.dee...@intel.com>
---
 drivers/gpu/drm/i915/intel_dsi.c               | 19 ++++++++++++++++
 drivers/gpu/drm/i915/intel_dsi.h               |  3 +++
 drivers/gpu/drm/i915/intel_dsi_dcs_backlight.c | 30 ++++++++++++++++++++++++++
 3 files changed, 52 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
index 1ba757a..a7b2949 100644
--- a/drivers/gpu/drm/i915/intel_dsi.c
+++ b/drivers/gpu/drm/i915/intel_dsi.c
@@ -1229,9 +1229,28 @@ void intel_dsi_init(struct drm_device *dev)
                default:
                        intel_dsi->panel_pwm_dcs_ports = BIT(PORT_A) | 
BIT(PORT_C);
                }
+
+               /*
+                * Based on the VBT value assign the ports on
+                * which CABC ON/OFF comands needs to be sent
+                */
+               switch (dev_priv->vbt.dsi.config->dl_cabc_ports) {
+               case CABC_PORT_A:
+                       intel_dsi->cabc_dcs_ports = BIT(PORT_A);
+                       break;
+               case CABC_PORT_C:
+                       intel_dsi->cabc_dcs_ports = BIT(PORT_C);
+                       break;
+               case CABC_PORT_A_AND_C:
+                       intel_dsi->cabc_dcs_ports = BIT(PORT_A) | BIT(PORT_C);
+                       break;
+               default:
+                       intel_dsi->cabc_dcs_ports = BIT(PORT_A) | BIT(PORT_C);
+               }
        } else {
                intel_dsi->ports = BIT(port);
                intel_dsi->panel_pwm_dcs_ports = BIT(port);
+                intel_dsi->cabc_dcs_ports = BIT(port);
        }
 
        /* Create a DSI host (and a device) for each port. */
diff --git a/drivers/gpu/drm/i915/intel_dsi.h b/drivers/gpu/drm/i915/intel_dsi.h
index dcd2265..322eebd 100644
--- a/drivers/gpu/drm/i915/intel_dsi.h
+++ b/drivers/gpu/drm/i915/intel_dsi.h
@@ -37,6 +37,9 @@
 #define PANEL_PWM_PORT_A               0x00
 #define PANEL_PWM_PORT_C               0x01
 #define PANEL_PWM_PORT_A_AND_C         0x02
+#define CABC_PORT_A                    0x00
+#define CABC_PORT_C                    0x01
+#define CABC_PORT_A_AND_C              0x02
 
 struct intel_dsi_host;
 
diff --git a/drivers/gpu/drm/i915/intel_dsi_dcs_backlight.c 
b/drivers/gpu/drm/i915/intel_dsi_dcs_backlight.c
index 4d7f0eb..5417f80 100644
--- a/drivers/gpu/drm/i915/intel_dsi_dcs_backlight.c
+++ b/drivers/gpu/drm/i915/intel_dsi_dcs_backlight.c
@@ -33,6 +33,11 @@
 #define PANEL_PWM_DISP_DIMMING         (1 << 3)
 #define PANEL_PWM_BCTRL                        (1 << 5)
 
+#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 PANEL_PWM_MAX_VALUE            0xFF
 
 static u32 panel_pwm_get_backlight(struct intel_connector *connector)
@@ -81,6 +86,8 @@ static void panel_pwm_set_backlight(struct intel_connector 
*connector, u32 level
 
 static void panel_pwm_disable_backlight(struct intel_connector *connector)
 {
+       struct drm_device *dev = connector->base.dev;
+       struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_encoder *encoder = connector->encoder;
        struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
        struct mipi_dsi_device *dsi_device;
@@ -89,6 +96,16 @@ static void panel_pwm_disable_backlight(struct 
intel_connector *connector)
 
        panel_pwm_set_backlight(connector, 0);
 
+       if (dev_priv->vbt.dsi.config->cabc_supported) {
+               data = 0;
+               for_each_dsi_port(port, intel_dsi->cabc_dcs_ports) {
+                       dsi_device = intel_dsi->dsi_hosts[port]->device;
+                       data = CABC_OFF;
+                       mipi_dsi_dcs_write(dsi_device, 
MIPI_DCS_WRITE_POWER_SAVE,
+                                       &data, sizeof(data));
+               }
+       }
+
        for_each_dsi_port(port, intel_dsi->panel_pwm_dcs_ports) {
                dsi_device = intel_dsi->dsi_hosts[port]->device;
                data &= ~PANEL_PWM_BKL_EN; /* Turn Off Backlight */
@@ -101,6 +118,8 @@ static void panel_pwm_disable_backlight(struct 
intel_connector *connector)
 
 static void panel_pwm_enable_backlight(struct intel_connector *connector)
 {
+       struct drm_device *dev = connector->base.dev;
+       struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_encoder *encoder = connector->encoder;
        struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
        struct intel_panel *panel = &connector->panel;
@@ -117,6 +136,17 @@ static void panel_pwm_enable_backlight(struct 
intel_connector *connector)
                                        &data, sizeof(data));
        }
 
+       if (dev_priv->vbt.dsi.config->cabc_supported) {
+               data = 0;
+               for_each_dsi_port(port, intel_dsi->cabc_dcs_ports) {
+                       dsi_device = intel_dsi->dsi_hosts[port]->device;
+                       /* Enabling CABC in still mode */
+                       data = CABC_STILL_PICTURE;
+                       mipi_dsi_dcs_write(dsi_device, 
MIPI_DCS_WRITE_POWER_SAVE,
+                                       &data, sizeof(data));
+               }
+       }
+
        panel_pwm_set_backlight(connector, panel->backlight.level);
 }
 
-- 
1.9.1

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