[Intel-gfx] [PATCH] drm/i915: Parsing LFP brightness control from VBT

[Vandana Kannan]

From: Deepak M <m.deepak at intel.com>

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 are for Control pin
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

History:
This patch was submitted earlier including a check for control pin.
http://lists.freedesktop.org/archives/intel-gfx/2014-December/057530.html
Since it caused the issue, https://bugs.freedesktop.org/show_bug.cgi?id=87671,
it was reverted in
http://lists.freedesktop.org/archives/intel-gfx/2015-January/058110.html

The current patch reads controller and control pin from VBT (version >= 191)

>From VBT version >= 197, default value of control pin is set to DDI, so the
corresponding check during backlight setup will be made in a future patch

Signed-off-by: Deepak M <m.deepak at intel.com>
Signed-off-by: Vandana Kannan <vandana.kannan at intel.com>
Cc: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h   |  2 ++
 drivers/gpu/drm/i915/intel_bios.c |  9 +++++++++
 drivers/gpu/drm/i915/intel_bios.h | 11 +++++++++++
 3 files changed, 22 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 950a981..a89e9a9 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1461,6 +1461,8 @@ struct intel_vbt_data {
 		bool present;
 		bool active_low_pwm;
 		u8 min_brightness;	/* min_brightness/255 of max */
+		u8 controller;		/* brightness controller number */
+		u8 control_pin;         /* brightness control pin */
 	} backlight;
 
 	/* MIPI DSI */
diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index 2ff9eb0..32c1ef2 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -256,6 +256,7 @@ parse_lfp_backlight(struct drm_i915_private *dev_priv,
 {
 	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)
@@ -268,6 +269,7 @@ parse_lfp_backlight(struct drm_i915_private *dev_priv,
 	}
 
 	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) {
@@ -279,12 +281,19 @@ parse_lfp_backlight(struct drm_i915_private *dev_priv,
 	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 = bl_ctrl_data->controller;
+	dev_priv->vbt.backlight.control_pin = bl_ctrl_data->pin;
+
 	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, BL control pin %u\n",
+			dev_priv->vbt.backlight.controller,
+			dev_priv->vbt.backlight.control_pin);
 }
 
 /* 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 af0b476..e97c1c0 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