From: Deepak M <[email protected]>

LFP brighness control from the VBT block 43 indicates which
controller is used for brightness.
LFP1 brightness control method:
Bit 7-4 = This field controller number of the brightnes controller.
0 = Controller 0
1 = Controller 1
2 = Controller 2
3 = Controller 3
Others = Reserved
Bits 3-0 = This field specifies the brightness control pin to be used on the
platform.
0 = PMIC pin is used for brightness control
1 = LPSS PWM is used for brightness control
2 = Display DDI is used for brightness control
3 = CABC method to control brightness
Others = Reserved

Adding the above fields in dev_priv->vbt and corresponding changes in
parse_backlight()

v2: Jani's review comments addressed
        - Move PWM definitions to intel_bios.h
        - Moving vbt_version to intel_vbt_data
        - Rename brightness to bl_ctrl_data
        - Logging just control_pin instead of string
        - Avoid adding vbt_version in dev_priv
        - Since only DDI option is available as of now, let control pin DDI
        affect dev_priv->vbt.backlight.present

v3: Jani's review comments addressed
        - Drop control_pin
        - Use bdb->version
        - set controller to 0 instead of using control pin define
        - check controller bounds
        - remove superfluous changes in intel_parse_bios

Signed-off-by: Deepak M <[email protected]>
Signed-off-by: Vandana Kannan <[email protected]>
Reviewed-by: Jani Nikula <[email protected]>
---
 drivers/gpu/drm/i915/i915_drv.h   |  1 +
 drivers/gpu/drm/i915/intel_bios.c | 20 ++++++++++++++++++++
 drivers/gpu/drm/i915/intel_bios.h | 11 +++++++++++
 3 files changed, 32 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 11e85cb..f4fef28 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1355,6 +1355,7 @@ struct intel_vbt_data {
                bool present;
                bool active_low_pwm;
                u8 min_brightness;      /* min_brightness/255 of max */
+               u8 controller;          /* brightness controller number */
        } backlight;
 
        /* MIPI DSI */
diff --git a/drivers/gpu/drm/i915/intel_bios.c 
b/drivers/gpu/drm/i915/intel_bios.c
index 3f17825..65b1fbc 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -314,6 +314,7 @@ parse_lfp_backlight(struct drm_i915_private *dev_priv, 
struct bdb_header *bdb)
 {
        const struct bdb_lfp_backlight_data *backlight_data;
        const struct bdb_lfp_backlight_data_entry *entry;
+       const struct bdb_lfp_backlight_control_data *bl_ctrl_data;
 
        backlight_data = find_section(bdb, BDB_LVDS_BACKLIGHT);
        if (!backlight_data)
@@ -326,6 +327,7 @@ parse_lfp_backlight(struct drm_i915_private *dev_priv, 
struct bdb_header *bdb)
        }
 
        entry = &backlight_data->data[panel_type];
+       bl_ctrl_data = &backlight_data->blc_ctl[panel_type];
 
        dev_priv->vbt.backlight.present = entry->type == BDB_BACKLIGHT_TYPE_PWM;
        if (!dev_priv->vbt.backlight.present) {
@@ -337,12 +339,30 @@ parse_lfp_backlight(struct drm_i915_private *dev_priv, 
struct bdb_header *bdb)
        dev_priv->vbt.backlight.pwm_freq_hz = entry->pwm_freq_hz;
        dev_priv->vbt.backlight.active_low_pwm = entry->active_low_pwm;
        dev_priv->vbt.backlight.min_brightness = entry->min_brightness;
+
+       dev_priv->vbt.backlight.controller = 0;
+       if (bdb->version >= 191) {
+               dev_priv->vbt.backlight.present =
+                               bl_ctrl_data->pin == BLC_CONTROL_PIN_DDI;
+               if (!dev_priv->vbt.backlight.present) {
+                       DRM_DEBUG_KMS("BL control pin is not DDI (pin %u)\n",
+                                       bl_ctrl_data->pin);
+                       return;
+               }
+               if (bl_ctrl_data->controller == 1)
+                       dev_priv->vbt.backlight.controller =
+                               bl_ctrl_data->controller;
+       }
+
        DRM_DEBUG_KMS("VBT backlight PWM modulation frequency %u Hz, "
                      "active %s, min brightness %u, level %u\n",
                      dev_priv->vbt.backlight.pwm_freq_hz,
                      dev_priv->vbt.backlight.active_low_pwm ? "low" : "high",
                      dev_priv->vbt.backlight.min_brightness,
                      backlight_data->level[panel_type]);
+
+       DRM_DEBUG_KMS("VBT BL controller %u\n",
+               dev_priv->vbt.backlight.controller);
 }
 
 /* Try to find sdvo panel data */
diff --git a/drivers/gpu/drm/i915/intel_bios.h 
b/drivers/gpu/drm/i915/intel_bios.h
index a6a8710..9a7202e 100644
--- a/drivers/gpu/drm/i915/intel_bios.h
+++ b/drivers/gpu/drm/i915/intel_bios.h
@@ -402,10 +402,21 @@ struct bdb_lfp_backlight_data_entry {
        u8 obsolete3;
 } __packed;
 
+#define BLC_CONTROL_PIN_PMIC           0
+#define BLC_CONTROL_PIN_LPSS_PWM       1
+#define BLC_CONTROL_PIN_DDI            2
+#define BLC_CONTROL_PIN_CABC           3
+
+struct bdb_lfp_backlight_control_data {
+       u8 controller:4;
+       u8 pin:4;
+} __packed;
+
 struct bdb_lfp_backlight_data {
        u8 entry_size;
        struct bdb_lfp_backlight_data_entry data[16];
        u8 level[16];
+       struct bdb_lfp_backlight_control_data blc_ctl[16];
 } __packed;
 
 struct aimdb_header {
-- 
2.0.1

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