[Intel-gfx] [PATCH 1/5] drm/i915: Adding VBT fields to support eDP DRRS feature

[Vandana Kannan]

From: Pradeep Bhat <pradeep.bhat at intel.com>

This patch reads the DRRS support and Mode type from VBT fields.
The read information will be stored in VBT struct during BIOS
parsing. The above functionality is needed for decision making
whether DRRS feature is supported in i915 driver for eDP panels.
This information helps us decide if seamless DRRS can be done
at runtime to support certain power saving features. This patch
was tested by setting necessary bit in VBT struct and merging
the new VBT with system BIOS so that we can read the value.

v2: Incorporated review comments from Chris Wilson
Removed "intel_" as a prefix for DRRS specific declarations.

Signed-off-by: Pradeep Bhat <pradeep.bhat at intel.com>
Signed-off-by: Vandana Kannan <vandana.kannan at intel.com>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_drv.h   |    9 +++++++++
 drivers/gpu/drm/i915/intel_bios.c |   23 +++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_bios.h |   29 +++++++++++++++++++++++++++++
 3 files changed, 61 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 64ed8f4..4d6665b 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1175,6 +1175,15 @@ struct intel_vbt_data {
 	int lvds_ssc_freq;
 	unsigned int bios_lvds_val; /* initial [PCH_]LVDS reg val in VBIOS */
 
+	/**
+	 * DRRS mode type (Seamless OR Static DRRS)
+	 * drrs_mode Val 0x2 is Seamless DRRS and 0 is Static DRRS.
+	 * These values correspond to the VBT values for drrs mode.
+	 */
+	int drrs_mode;
+	/* DRRS enabled or disabled in VBT */
+	bool drrs_enabled;
+
 	/* eDP */
 	int edp_rate;
 	int edp_lanes;
diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index 6dd622d..30ab5a3 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -195,6 +195,21 @@ get_lvds_fp_timing(const struct bdb_header *bdb,
 	return (const struct lvds_fp_timing *)((const u8 *)bdb + ofs);
 }
 
+/**
+ * This function returns the 2 bit information pertaining to a panel type
+ * present in a 32 bit field in VBT blocks. There are 16 panel types in VBT
+ * each occupying 2 bits of information in some 32 bit fields of VBT blocks.
+ */
+static int
+get_mode_by_paneltype(unsigned int word)
+{
+	/**
+	 * The caller of this API should interpret the 2 bits
+	 * based on VBT description for that field.
+	 */
+	return (word >> ((panel_type - 1) * 2)) & MODE_MASK;
+}
+
 /* Try to find integrated panel data */
 static void
 parse_lfp_panel_data(struct drm_i915_private *dev_priv,
@@ -218,6 +233,11 @@ parse_lfp_panel_data(struct drm_i915_private *dev_priv,
 
 	panel_type = lvds_options->panel_type;
 
+	dev_priv->vbt.drrs_mode =
+		get_mode_by_paneltype(lvds_options->dps_panel_type_bits);
+	DRM_DEBUG_KMS("DRRS supported mode is : %s\n",
+			(dev_priv->vbt.drrs_mode == 0) ? "STATIC" : "SEAMLESS");
+
 	lvds_lfp_data = find_section(bdb, BDB_LVDS_LFP_DATA);
 	if (!lvds_lfp_data)
 		return;
@@ -488,6 +508,9 @@ parse_driver_features(struct drm_i915_private *dev_priv,
 
 	if (driver->dual_frequency)
 		dev_priv->render_reclock_avail = true;
+
+	dev_priv->vbt.drrs_enabled = driver->drrs_state;
+	DRM_DEBUG_KMS("DRRS State Enabled : %d\n", driver->drrs_state);
 }
 
 static void
diff --git a/drivers/gpu/drm/i915/intel_bios.h b/drivers/gpu/drm/i915/intel_bios.h
index f580a2b..8e594f6 100644
--- a/drivers/gpu/drm/i915/intel_bios.h
+++ b/drivers/gpu/drm/i915/intel_bios.h
@@ -202,6 +202,9 @@ struct bdb_general_features {
 #define DEVICE_PORT_DVOB	0x01
 #define DEVICE_PORT_DVOC	0x02
 
+/* Mask for DRRS / Panel Channel / SSC / BLT control bits extraction */
+#define MODE_MASK		0x3
+
 /* We used to keep this struct but without any version control. We should avoid
  * using it in the future, but it should be safe to keep using it in the old
  * code. */
@@ -293,6 +296,18 @@ struct bdb_lvds_options {
 	u8 lvds_edid:1;
 	u8 rsvd2:1;
 	u8 rsvd4;
+	/* LVDS Panel channel bits stored here */
+	u32 lvds_panel_channel_bits;
+	/* LVDS SSC (Spread Spectrum Clock) bits stored here. */
+	u16 ssc_bits;
+	u16 ssc_freq;
+	u16 ssc_ddt;
+	/* Panel color depth defined here */
+	u16 panel_color_depth;
+	/* LVDS panel type bits stored here */
+	u32 dps_panel_type_bits;
+	/* LVDS backlight control type bits stored here */
+	u32 blt_control_type_bits;
 } __attribute__((packed));
 
 /* LFP pointer table contains entries to the struct below */
@@ -462,6 +477,20 @@ struct bdb_driver_features {
 
 	u8 hdmi_termination;
 	u8 custom_vbt_version;
+	/* Driver features data block */
+	u16 rmpm_state:1;
+	u16 s2ddt_state:1;
+	u16 dpst_state:1;
+	u16 bltclt_state:1;
+	u16 adb_state:1;
+	u16 drrs_state:1;
+	u16 grs_state:1;
+	u16 gpmt_state:1;
+	u16 tbt_state:1;
+	u16 psr_state:1;
+	u16 ips_state:1;
+	u16 reserved3:4;
+	u16 pc_feature_validity:1;
 } __attribute__((packed));
 
 #define EDP_18BPP	0
-- 
1.7.9.5