sys/eve: fix backlight adjustment

4 files changed, 403 insertions, 1 deletions

diff --git a/overlays/patches/default.nix b/overlays/patches/default.nix
index b7c2f7b7f6bd..63f5e53441e4 100644
--- a/overlays/patches/default.nix
+++ b/overlays/patches/default.nix
@@ -20,6 +20,8 @@ self: super: {
 
   gnupg = self.callPackage ./gnupg { inherit (super) gnupg; };
 
+  kernelPatches = self.callPackage ./linux/patches.nix { inherit (super) kernelPatches; };
+
   public-inbox = self.callPackage ./public-inbox {
     inherit (super) public-inbox;
   };
diff --git a/overlays/patches/linux/eve-backlight.patch b/overlays/patches/linux/eve-backlight.patch
new file mode 100644
index 000000000000..dcf1cc5505ea
--- /dev/null
+++ b/overlays/patches/linux/eve-backlight.patch
@@ -0,0 +1,392 @@
+From 0154de6abf4f81c5d81b8391e931dc1f7071182f Mon Sep 17 00:00:00 2001
+From: Alyssa Ross <hi@alyssa.is>
+Date: Sun, 25 Apr 2021 08:19:45 +0000
+Subject: [PATCH 1/2] Revert "drm/i915/vbt: Fix backlight parsing for VBT 234+"
+
+This reverts commit d381baad29b43511a7fc34c64402ef65029ab281.
+---
+ drivers/gpu/drm/i915/display/intel_bios.c     | 30 ++-----------------
+ drivers/gpu/drm/i915/display/intel_vbt_defs.h | 12 ++------
+ 2 files changed, 4 insertions(+), 38 deletions(-)
+
+diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
+index 4cc949b228f2d..f12975ef92428 100644
+--- a/drivers/gpu/drm/i915/display/intel_bios.c
++++ b/drivers/gpu/drm/i915/display/intel_bios.c
+@@ -425,7 +425,6 @@ parse_lfp_backlight(struct drm_i915_private *dev_priv,
+ 	const struct bdb_lfp_backlight_data *backlight_data;
+ 	const struct lfp_backlight_data_entry *entry;
+ 	int panel_type = dev_priv->vbt.panel_type;
+-	u16 level;
+ 
+ 	backlight_data = find_section(bdb, BDB_LVDS_BACKLIGHT);
+ 	if (!backlight_data)
+@@ -460,39 +459,14 @@ 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;
+-
+-	if (bdb->version >= 234) {
+-		u16 min_level;
+-		bool scale;
+-
+-		level = backlight_data->brightness_level[panel_type].level;
+-		min_level = backlight_data->brightness_min_level[panel_type].level;
+-
+-		if (bdb->version >= 236)
+-			scale = backlight_data->brightness_precision_bits[panel_type] == 16;
+-		else
+-			scale = level > 255;
+-
+-		if (scale)
+-			min_level = min_level / 255;
+-
+-		if (min_level > 255) {
+-			drm_warn(&dev_priv->drm, "Brightness min level > 255\n");
+-			level = 255;
+-		}
+-		dev_priv->vbt.backlight.min_brightness = min_level;
+-	} else {
+-		level = backlight_data->level[panel_type];
+-		dev_priv->vbt.backlight.min_brightness = entry->min_brightness;
+-	}
+-
++	dev_priv->vbt.backlight.min_brightness = entry->min_brightness;
+ 	drm_dbg_kms(&dev_priv->drm,
+ 		    "VBT backlight PWM modulation frequency %u Hz, "
+ 		    "active %s, min brightness %u, level %u, controller %u\n",
+ 		    dev_priv->vbt.backlight.pwm_freq_hz,
+ 		    dev_priv->vbt.backlight.active_low_pwm ? "low" : "high",
+ 		    dev_priv->vbt.backlight.min_brightness,
+-		    level,
++		    backlight_data->level[panel_type],
+ 		    dev_priv->vbt.backlight.controller);
+ }
+ 
+diff --git a/drivers/gpu/drm/i915/display/intel_vbt_defs.h b/drivers/gpu/drm/i915/display/intel_vbt_defs.h
+index 49b4b5fca9411..9abdde1e68dc4 100644
+--- a/drivers/gpu/drm/i915/display/intel_vbt_defs.h
++++ b/drivers/gpu/drm/i915/display/intel_vbt_defs.h
+@@ -782,7 +782,7 @@ struct lfp_backlight_data_entry {
+ 	u8 active_low_pwm:1;
+ 	u8 obsolete1:5;
+ 	u16 pwm_freq_hz;
+-	u8 min_brightness; /* Obsolete from 234+ */
++	u8 min_brightness;
+ 	u8 obsolete2;
+ 	u8 obsolete3;
+ } __packed;
+@@ -792,19 +792,11 @@ struct lfp_backlight_control_method {
+ 	u8 controller:4;
+ } __packed;
+ 
+-struct lfp_brightness_level {
+-	u16 level;
+-	u16 reserved;
+-} __packed;
+-
+ struct bdb_lfp_backlight_data {
+ 	u8 entry_size;
+ 	struct lfp_backlight_data_entry data[16];
+-	u8 level[16]; /* Obsolete from 234+ */
++	u8 level[16];
+ 	struct lfp_backlight_control_method backlight_control[16];
+-	struct lfp_brightness_level brightness_level[16];		/* 234+ */
+-	struct lfp_brightness_level brightness_min_level[16];	/* 234+ */
+-	u8 brightness_precision_bits[16];						/* 236+ */
+ } __packed;
+ 
+ /*
+-- 
+2.31.0
+
+From 280a1737103195768814b62e0b0b3d646a961c4a Mon Sep 17 00:00:00 2001
+From: Kevin Chowski <chowski@google.com>
+Date: Sat, 8 Aug 2020 15:40:51 -0600
+Subject: [PATCH 2/2] CHROMIUM: Changes needed for backlight control on Eve-5.4
+
+ #1: Port https://crrev.com/c/439873 to the 5.4 tree
+ #2: Port https://crrev.com/c/440445 to the 5.4 tree
+ #3: Port https://crrev.com/c/456118 to the 5.4 tree
+
+The first two patches are needed to correctly enable the backlight for
+Eve; they were submitted upstream in 2017 but were rolled back.
+
+The third patch was not rolled back upstream, but the code related to it
+changed quite a bit between 4.4 and 5.4: the write of
+DP_EDP_PWMGEN_BIT_COUNT used to happen on every screen enable via
+intel_dp_aux_set_pwm_freq (that's how it works in 4.4), but in 5.4 the
+write was refactored into intel_dp_aux_calc_max_backlight and only
+called once per screen setup. This patch brings back the old
+functionality of intel_dp_aux_set_pwm_freq to ensure we set that
+register on each screen enable, but this is at the cost of duplication
+between intel_dp_aux_calc_max_backlight. Unfortunately, I don't see a
+better way to do this without making the cros code diverge even further
+from 4.4 and 5.4.
+
+I'd like to submit this CL into the chromium tree, and use b/163412221
+to track its upstreaming and the ultimate revert of this change.
+
+Test:
+   * `emerge-eve-kernelnext sys-kernel/chromeos-kernel-5_4`
+   * `./update_kernel.sh --remote=192.168.0.22 --remote_bootarg`
+   * On DUT, set options `i915.enable_dpcd_backlight=1 i915.enable_dbc=1`
+     (using e.g. `/usr/share/vboot/bin/make_dev_ssd.sh`)
+   * reboot
+   * Change brightness on DUT
+   * Allow DUT screen to fall asleep
+   * Wake DUT screen, change brightness again
+
+BUG=b:162255390
+TEST=See above
+
+Change-Id: I9eafa28226f1c6b8332fcf9730259bea05cf7975
+Signed-off-by: Kevin Chowski <chowski@google.com>
+Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2344844
+Reviewed-by: Puthikorn Voravootivat <puthik@chromium.org>
+Conflicts:
+	drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+[rebase510(groeck): Picked code from continuous rebase project to resolve conflicts]
+Signed-off-by: Guenter Roeck <groeck@chromium.org>
+(cherry picked from commit 37af4b996c1e25b7be4a00e5c5bcf29bc37cd51a)
+---
+ .../drm/i915/display/intel_dp_aux_backlight.c | 143 ++++++++++++++++--
+ drivers/gpu/drm/i915/i915_params.c            |   3 +
+ drivers/gpu/drm/i915/i915_params.h            |   3 +-
+ 3 files changed, 139 insertions(+), 10 deletions(-)
+
+diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+index 51d27fc98d483..d76888863e7cf 100644
+--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
++++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+@@ -141,10 +141,16 @@ static bool intel_dp_aux_set_pwm_freq(struct intel_connector *connector)
+ {
+ 	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
+ 	struct intel_dp *intel_dp = intel_attached_dp(connector);
+-	const u8 pn = connector->panel.backlight.pwmgen_bit_count;
+-	int freq, fxp, f, fxp_actual, fxp_min, fxp_max;
++	int freq, fxp, fxp_min, fxp_max, fxp_actual, f = 1;
++	u8 pn, pn_min, pn_max;
+ 
++	/* Find desired value of (F x P)
++	 * Note that, if F x P is out of supported range, the maximum value or
++	 * minimum value will applied automatically. So no need to check that.
++	 */
+ 	freq = dev_priv->vbt.backlight.pwm_freq_hz;
++	drm_dbg_kms(&dev_priv->drm,
++		    "VBT defined backlight frequency %u Hz\n", freq);
+ 	if (!freq) {
+ 		drm_dbg_kms(&dev_priv->drm,
+ 			    "Use panel default backlight frequency\n");
+@@ -152,18 +158,50 @@ static bool intel_dp_aux_set_pwm_freq(struct intel_connector *connector)
+ 	}
+ 
+ 	fxp = DIV_ROUND_CLOSEST(KHz(DP_EDP_BACKLIGHT_FREQ_BASE_KHZ), freq);
+-	f = clamp(DIV_ROUND_CLOSEST(fxp, 1 << pn), 1, 255);
+-	fxp_actual = f << pn;
+ 
+-	/* Ensure frequency is within 25% of desired value */
++	/* Use highest possible value of Pn for more granularity of brightness
++	 * adjustment while satifying the conditions below.
++	 * - Pn is in the range of Pn_min and Pn_max
++	 * - F is in the range of 1 and 255
++	 * - FxP is within 25% of desired value.
++	 *   Note: 25% is arbitrary value and may need some tweak.
++	 */
++	if (drm_dp_dpcd_readb(&intel_dp->aux,
++			       DP_EDP_PWMGEN_BIT_COUNT_CAP_MIN, &pn_min) != 1) {
++		drm_dbg_kms(&dev_priv->drm,
++			    "Failed to read pwmgen bit count cap min\n");
++		return false;
++	}
++	if (drm_dp_dpcd_readb(&intel_dp->aux,
++			       DP_EDP_PWMGEN_BIT_COUNT_CAP_MAX, &pn_max) != 1) {
++		drm_dbg_kms(&dev_priv->drm,
++			    "Failed to read pwmgen bit count cap max\n");
++		return false;
++	}
++	pn_min &= DP_EDP_PWMGEN_BIT_COUNT_MASK;
++	pn_max &= DP_EDP_PWMGEN_BIT_COUNT_MASK;
++
+ 	fxp_min = DIV_ROUND_CLOSEST(fxp * 3, 4);
+ 	fxp_max = DIV_ROUND_CLOSEST(fxp * 5, 4);
+-
+-	if (fxp_min > fxp_actual || fxp_actual > fxp_max) {
+-		drm_dbg_kms(&dev_priv->drm, "Actual frequency out of range\n");
++	if (fxp_min < (1 << pn_min) || (255 << pn_max) < fxp_max) {
++		drm_dbg_kms(&dev_priv->drm,
++			    "VBT defined backlight frequency out of range\n");
+ 		return false;
+ 	}
+ 
++	for (pn = pn_max; pn >= pn_min; pn--) {
++		f = clamp(DIV_ROUND_CLOSEST(fxp, 1 << pn), 1, 255);
++		fxp_actual = f << pn;
++		if (fxp_min <= fxp_actual && fxp_actual <= fxp_max)
++			break;
++	}
++
++	if (drm_dp_dpcd_writeb(&intel_dp->aux,
++			       DP_EDP_PWMGEN_BIT_COUNT, pn) < 0) {
++		drm_dbg_kms(&dev_priv->drm,
++			    "Failed to write aux pwmgen bit count\n");
++		return false;
++	}
+ 	if (drm_dp_dpcd_writeb(&intel_dp->aux,
+ 			       DP_EDP_BACKLIGHT_FREQ_SET, (u8) f) < 0) {
+ 		drm_dbg_kms(&dev_priv->drm,
+@@ -173,6 +211,26 @@ static bool intel_dp_aux_set_pwm_freq(struct intel_connector *connector)
+ 	return true;
+ }
+ 
++/*
++ * Set minimum / maximum dynamic brightness percentage. This value is expressed
++ * as the percentage of normal brightness in 5% increments.
++ */
++static bool
++intel_dp_aux_set_dynamic_backlight_percent(struct intel_dp *intel_dp,
++					   u32 min, u32 max)
++{
++	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
++	u8 dbc[] = { DIV_ROUND_CLOSEST(min, 5), DIV_ROUND_CLOSEST(max, 5) };
++
++	if (drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_DBC_MINIMUM_BRIGHTNESS_SET,
++			  dbc, sizeof(dbc)) < 0) {
++		drm_dbg_kms(&i915->drm,
++			    "Failed to write aux DBC brightness level\n");
++		return false;
++	}
++	return true;
++}
++
+ static void intel_dp_aux_enable_backlight(const struct intel_crtc_state *crtc_state,
+ 					  const struct drm_connector_state *conn_state)
+ {
+@@ -213,6 +271,16 @@ static void intel_dp_aux_enable_backlight(const struct intel_crtc_state *crtc_st
+ 		break;
+ 	}
+ 
++	if (i915_modparams.enable_dbc &&
++	    (intel_dp->edp_dpcd[2] & DP_EDP_DYNAMIC_BACKLIGHT_CAP)) {
++		if (intel_dp_aux_set_dynamic_backlight_percent(intel_dp,
++						0, 100)) {
++			new_dpcd_buf |= DP_EDP_DYNAMIC_BACKLIGHT_ENABLE;
++			drm_dbg_kms(&i915->drm,
++				    "Enable dynamic brightness.\n");
++		}
++	}
++
+ 	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_FREQ_AUX_SET_CAP)
+ 		if (intel_dp_aux_set_pwm_freq(connector))
+ 			new_dpcd_buf |= DP_EDP_BACKLIGHT_FREQ_AUX_SET_ENABLE;
+@@ -342,7 +410,7 @@ intel_dp_aux_display_control_capable(struct intel_connector *connector)
+ 	/* Check the eDP Display control capabilities registers to determine if
+ 	 * the panel can support backlight control over the aux channel
+ 	 */
+-	if (intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP &&
++	if ((intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP) &&
+ 	    (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP)) {
+ 		drm_dbg_kms(&i915->drm, "AUX Backlight Control Supported!\n");
+ 		return true;
+@@ -350,6 +418,59 @@ intel_dp_aux_display_control_capable(struct intel_connector *connector)
+ 	return false;
+ }
+ 
++/*
++ * Heuristic function whether we should use AUX for backlight adjustment or not.
++ *
++ * We should use AUX for backlight brightness adjustment if panel doesn't this
++ * via PWM pin or using AUX is better than using PWM pin.
++ *
++ * The heuristic to determine that using AUX pin is better than using PWM pin is
++ * that the panel support any of the feature list here.
++ * - Regional backlight brightness adjustment
++ * - Backlight PWM frequency set
++ * - More than 8 bits resolution of brightness level
++ * - Backlight enablement via AUX and not by BL_ENABLE pin
++ *
++ * If all above are not true, assume that using PWM pin is better.
++ */
++static bool
++intel_dp_aux_display_control_heuristic(struct intel_connector *connector)
++{
++	struct intel_dp *intel_dp = intel_attached_dp(connector);
++	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
++	uint8_t reg_val;
++
++	/* Panel doesn't support adjusting backlight brightness via PWN pin */
++	if (!(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP))
++		return true;
++
++	/* Panel supports regional backlight brightness adjustment */
++	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_GENERAL_CAP_3,
++			      &reg_val) != 1) {
++		drm_dbg_kms(&i915->drm, "Failed to read DPCD register 0x%x\n",
++			       DP_EDP_GENERAL_CAP_3);
++		return false;
++	}
++	if (reg_val > 0)
++		return true;
++
++	/* Panel supports backlight PWM frequency set */
++	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_FREQ_AUX_SET_CAP)
++		return true;
++
++	/* Panel supports more than 8 bits resolution of brightness level */
++	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
++		return true;
++
++	/* Panel supports enabling backlight via AUX but not by BL_ENABLE pin */
++	if ((intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&
++	    !(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_PIN_ENABLE_CAP))
++		return true;
++
++	return false;
++
++}
++
+ int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
+ {
+ 	struct intel_panel *panel = &intel_connector->panel;
+@@ -379,6 +500,10 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
+ 		return -ENODEV;
+ 	}
+ 
++	if (i915_modparams.enable_dpcd_backlight == -1 &&
++	    !intel_dp_aux_display_control_heuristic(intel_connector))
++		return -ENODEV;
++
+ 	panel->backlight.setup = intel_dp_aux_setup_backlight;
+ 	panel->backlight.enable = intel_dp_aux_enable_backlight;
+ 	panel->backlight.disable = intel_dp_aux_disable_backlight;
+diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
+index 7f139ea4a90b2..378fc905f2b78 100644
+--- a/drivers/gpu/drm/i915/i915_params.c
++++ b/drivers/gpu/drm/i915/i915_params.c
+@@ -187,6 +187,9 @@ i915_param_named(enable_dpcd_backlight, int, 0400,
+ 	"Enable support for DPCD backlight control"
+ 	"(-1=use per-VBT LFP backlight type setting [default], 0=disabled, 1=enabled)");
+ 
++i915_param_named(enable_dbc, bool, 0600,
++	"Enable support for dynamic backlight control (default:false)");
++
+ #if IS_ENABLED(CONFIG_DRM_I915_GVT)
+ i915_param_named(enable_gvt, bool, 0400,
+ 	"Enable support for Intel GVT-g graphics virtualization host support(default:false)");
+diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
+index 330c03e2b4f70..2340889d87834 100644
+--- a/drivers/gpu/drm/i915/i915_params.h
++++ b/drivers/gpu/drm/i915/i915_params.h
+@@ -80,7 +80,8 @@ struct drm_printer;
+ 	param(bool, verbose_state_checks, true, 0) \
+ 	param(bool, nuclear_pageflip, false, 0400) \
+ 	param(bool, enable_dp_mst, true, 0600) \
+-	param(bool, enable_gvt, false, 0400)
++	param(bool, enable_gvt, false, 0400) \
++	param(bool, enable_dbc, false, 0600)
+ 
+ #define MEMBER(T, member, ...) T member;
+ struct i915_params {
+-- 
+2.31.0
+
diff --git a/overlays/patches/linux/patches.nix b/overlays/patches/linux/patches.nix
new file mode 100644
index 000000000000..e7a7320f1e6c
--- /dev/null
+++ b/overlays/patches/linux/patches.nix
@@ -0,0 +1,5 @@
+{ kernelPatches, ... } @ args:
+
+(kernelPatches.override (builtins.removeAttrs args [ "kernelPatches" ])) // {
+  eve-backlight = { name = "eve-backlight"; patch = ./eve-backlight.patch; };
+}
diff --git a/sys/eve.nix b/sys/eve.nix
index 9f0c8cc5cc1f..86b8c9c08045 100644
--- a/sys/eve.nix
+++ b/sys/eve.nix
@@ -8,7 +8,10 @@
 
   hardware.enableRedistributableFirmware = true;
 
-  boot.kernelPackages = pkgs.linuxPackages_latest;
+  boot.kernelPackages = with pkgs; linuxPackagesFor (linux_latest.override {
+    kernelPatches =
+      linux_latest.kernelPatches ++ (with kernelPatches; [ eve-backlight ]);
+  });
 
   boot.initrd.availableKernelModules = [ "nvme" "usb_storage" "sdhci_pci" ];
   boot.kernelModules = [ "kvm-intel" ];