Add patch for AMDGPU backlight

2 files changed, 194 insertions, 1 deletions

diff --git a/PKGBUILD b/PKGBUILD
index b847c13e62fc..1284c7617efd 100644
--- a/PKGBUILD
+++ b/PKGBUILD
@@ -3,7 +3,7 @@
 pkgbase=linux-zen-g14
 _pkgbase=linux-zen
 pkgver=5.8.zen1
-pkgrel=2
+pkgrel=3
 pkgdesc='Linux ZEN with patch for Zephyrus G14 (GA401IV)'
 _srctag=v${pkgver%.*}-${pkgver##*.}
 url="https://github.com/zen-kernel/zen-kernel/commits/$_srctag"
@@ -22,6 +22,7 @@ source=(
   i8042.patch
   asus-nb-wmi.patch
   asus-n-key-keyboard.patch
+  amdgpu-backlight.patch
   "https://github.com/dolohow/uksm/raw/master/v5.x/uksm-5.8.patch"
 )
 validpgpkeys=(
@@ -34,6 +35,7 @@ sha256sums=('SKIP'
             '2273fae30f712aa554dd10294a072b4934265b56e6146493a07c22c7df4af61d'
             'ac8d8a0d54ad79e44f25b255bfecc80d190502e1173df18b091f53e9882d4ac8'
             'fdea6ab1672ea4758359e9c6e743aba56f33224c5d759852817a01af5974fd4b'
+            '7573ea16b7a54aba6b7b160051c1efa4fc3471c341a27bcfcc60e0ba832e409d'
             '0389c65d8357f8b22f65aceaf9ceda5a3c76e60ca34f713ff9a09ec379f51dc7')
 
 export KBUILD_BUILD_HOST=archlinux
diff --git a/amdgpu-backlight.patch b/amdgpu-backlight.patch
new file mode 100644
index 000000000000..6de8bf118240
--- /dev/null
+++ b/amdgpu-backlight.patch
@@ -0,0 +1,191 @@
+From mboxrd@z Thu Jan  1 00:00:00 1970
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+From:   Alexander Monakov <amonakov@ispras.ru>
+To:     amd-gfx@lists.freedesktop.org
+Cc:     linux-kernel@vger.kernel.org,
+        Alexander Monakov <amonakov@ispras.ru>,
+        Alex Deucher <alexander.deucher@amd.com>,
+        Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
+Subject: [PATCH v2] drm/amd/display: use correct scale for actual_brightness
+Date:   Tue,  4 Aug 2020 23:13:13 +0300
+Message-Id: <20200804201313.6464-1-amonakov@ispras.ru>
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+
+Documentation for sysfs backlight level interface requires that
+values in both 'brightness' and 'actual_brightness' files are
+interpreted to be in range from 0 to the value given in the
+'max_brightness' file.
+
+With amdgpu, max_brightness gives 255, and values written by the user
+into 'brightness' are internally rescaled to a wider range. However,
+reading from 'actual_brightness' gives the raw register value without
+inverse rescaling. This causes issues for various userspace tools such
+as PowerTop and systemd that expect the value to be in the correct
+range.
+
+Introduce a helper to retrieve internal backlight range. Use it to
+reimplement 'convert_brightness' as 'convert_brightness_from_user' and
+introduce 'convert_brightness_to_user'.
+
+Bug: https://bugzilla.kernel.org/show_bug.cgi?id=203905
+Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1242
+Cc: Alex Deucher <alexander.deucher@amd.com>
+Cc: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
+Signed-off-by: Alexander Monakov <amonakov@ispras.ru>
+---
+v2: split convert_brightness to &_from_user and &_to_user (Nicholas)
+
+ .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 81 +++++++++----------
+ 1 file changed, 40 insertions(+), 41 deletions(-)
+
+diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+index 710edc70e37e..b60a763f3f95 100644
+--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
++++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+@@ -2881,51 +2881,50 @@ static int set_backlight_via_aux(struct dc_link *link, uint32_t brightness)
+ 	return rc ? 0 : 1;
+ }
+ 
+-static u32 convert_brightness(const struct amdgpu_dm_backlight_caps *caps,
+-			      const uint32_t user_brightness)
++static int get_brightness_range(const struct amdgpu_dm_backlight_caps *caps,
++				unsigned *min, unsigned *max)
+ {
+-	u32 min, max, conversion_pace;
+-	u32 brightness = user_brightness;
+-
+ 	if (!caps)
+-		goto out;
++		return 0;
+ 
+-	if (!caps->aux_support) {
+-		max = caps->max_input_signal;
+-		min = caps->min_input_signal;
+-		/*
+-		 * The brightness input is in the range 0-255
+-		 * It needs to be rescaled to be between the
+-		 * requested min and max input signal
+-		 * It also needs to be scaled up by 0x101 to
+-		 * match the DC interface which has a range of
+-		 * 0 to 0xffff
+-		 */
+-		conversion_pace = 0x101;
+-		brightness =
+-			user_brightness
+-			* conversion_pace
+-			* (max - min)
+-			/ AMDGPU_MAX_BL_LEVEL
+-			+ min * conversion_pace;
++	if (caps->aux_support) {
++		// Firmware limits are in nits, DC API wants millinits.
++		*max = 1000 * caps->aux_max_input_signal;
++		*min = 1000 * caps->aux_min_input_signal;
+ 	} else {
+-		/* TODO
+-		 * We are doing a linear interpolation here, which is OK but
+-		 * does not provide the optimal result. We probably want
+-		 * something close to the Perceptual Quantizer (PQ) curve.
+-		 */
+-		max = caps->aux_max_input_signal;
+-		min = caps->aux_min_input_signal;
+-
+-		brightness = (AMDGPU_MAX_BL_LEVEL - user_brightness) * min
+-			       + user_brightness * max;
+-		// Multiple the value by 1000 since we use millinits
+-		brightness *= 1000;
+-		brightness = DIV_ROUND_CLOSEST(brightness, AMDGPU_MAX_BL_LEVEL);
++		// Firmware limits are 8-bit, PWM control is 16-bit.
++		*max = 0x101 * caps->max_input_signal;
++		*min = 0x101 * caps->min_input_signal;
+ 	}
++	return 1;
++}
+ 
+-out:
+-	return brightness;
++static u32 convert_brightness_from_user(const struct amdgpu_dm_backlight_caps *caps,
++					uint32_t brightness)
++{
++	unsigned min, max;
++
++	if (!get_brightness_range(caps, &min, &max))
++		return brightness;
++
++	// Rescale 0..255 to min..max
++	return min + DIV_ROUND_CLOSEST((max - min) * brightness,
++				       AMDGPU_MAX_BL_LEVEL);
++}
++
++static u32 convert_brightness_to_user(const struct amdgpu_dm_backlight_caps *caps,
++				      uint32_t brightness)
++{
++	unsigned min, max;
++
++	if (!get_brightness_range(caps, &min, &max))
++		return brightness;
++
++	if (brightness < min)
++		return 0;
++	// Rescale min..max to 0..255
++	return DIV_ROUND_CLOSEST(AMDGPU_MAX_BL_LEVEL * (brightness - min),
++				 max - min);
+ }
+ 
+ static int amdgpu_dm_backlight_update_status(struct backlight_device *bd)
+@@ -2941,7 +2940,7 @@ static int amdgpu_dm_backlight_update_status(struct backlight_device *bd)
+ 
+ 	link = (struct dc_link *)dm->backlight_link;
+ 
+-	brightness = convert_brightness(&caps, bd->props.brightness);
++	brightness = convert_brightness_from_user(&caps, bd->props.brightness);
+ 	// Change brightness based on AUX property
+ 	if (caps.aux_support)
+ 		return set_backlight_via_aux(link, brightness);
+@@ -2958,7 +2957,7 @@ static int amdgpu_dm_backlight_get_brightness(struct backlight_device *bd)
+ 
+ 	if (ret == DC_ERROR_UNEXPECTED)
+ 		return bd->props.brightness;
+-	return ret;
++	return convert_brightness_to_user(&dm->backlight_caps, ret);
+ }
+ 
+ static const struct backlight_ops amdgpu_dm_backlight_ops = {
+
+base-commit: bcf876870b95592b52519ed4aafcf9d95999bc9c
+-- 
+2.26.2
+
+