From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- Documentation/ABI/testing/sysfs-class-backlight | 186 ++++++++++++++++++++++++ 1 file changed, 186 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-class-backlight (limited to 'Documentation/ABI/testing/sysfs-class-backlight') diff --git a/Documentation/ABI/testing/sysfs-class-backlight b/Documentation/ABI/testing/sysfs-class-backlight new file mode 100644 index 000000000..c453646b0 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-class-backlight @@ -0,0 +1,186 @@ +What: /sys/class/backlight//scale +Date: July 2019 +KernelVersion: 5.4 +Contact: Daniel Thompson +Description: + Description of the scale of the brightness curve. + + The human eye senses brightness approximately logarithmically, + hence linear changes in brightness are perceived as being + non-linear. To achieve a linear perception of brightness changes + controls like sliders need to apply a logarithmic mapping for + backlights with a linear brightness curve. + + Possible values of the attribute are: + + unknown + The scale of the brightness curve is unknown. + + linear + The brightness changes linearly with each step. Brightness + controls should apply a logarithmic mapping for a linear + perception. + + non-linear + The brightness changes non-linearly with each step. Brightness + controls should use a linear mapping for a linear perception. + +What: /sys/class/backlight//ambient_light_level +Date: Apr, 2010 +KernelVersion: v2.6.35 +Contact: Michael Hennerich +Description: + (RO) Get conversion value of the light sensor. + + The value is automatically updated every 80 ms when the + light sensor is enabled. + + The value range is device-driver specific: + + For ADP8870: + + It returns integer between 0 (dark) and 8000 (max ambient + brightness). + + For ADP8860: + + It returns a 13-bits integer. + +What: /sys/class/backlight//ambient_light_zone +Date: Apr, 2010 +KernelVersion: v2.6.35 +Contact: Michael Hennerich , + device-drivers-devel@blackfin.uclinux.org + +Description: + (RW) Read or write the specific brightness level at which the + backlight operates. + + The value meaning is device-driver specific: + + For ADP8860: + + == ========================== + 0 Off: Backlight set to 0 mA + 1 Level 1: daylight + 2 Level 2: bright + 3 Level 3: dark + == ========================== + + For ADP8870: + + == ========================== + 0 Off: Backlight set to 0 mA + 1 Level 1: daylight + 2 Level 2: bright + 3 Level 3: office + 4 Level 4: indoor + 5 Level 5: dark + == ========================== + + Writing 0 returns to normal/automatic ambient light level + operation. + + It can be enabled by writing the value stored in + /sys/class/backlight//max_brightness to + /sys/class/backlight//brightness. + +What: /sys/class/backlight//_max +Date: Sep, 2009 +KernelVersion: v2.6.32 +Contact: device-drivers-devel@blackfin.uclinux.org +Description: + Control the maximum brightness for + on this . Values are between 0 and 127. This file + will also show the brightness level stored for this + . + + The is device-driver specific: + + For ADP5520 and ADP5501, can be: + + =========== ================================================ + Ambient sysfs entry + light zone + =========== ================================================ + daylight /sys/class/backlight//daylight_max + office /sys/class/backlight//office_max + dark /sys/class/backlight//dark_max + =========== ================================================ + + For ADP8860, can be: + + =========== ================================================ + Ambient sysfs entry + light zone + =========== ================================================ + l1_daylight /sys/class/backlight//l1_daylight_max + l2_office /sys/class/backlight//l2_office_max + l3_dark /sys/class/backlight//l3_dark_max + =========== ================================================ + + For ADP8870, can be: + + =========== ================================================ + Ambient sysfs entry + light zone + =========== ================================================ + l1_daylight /sys/class/backlight//l1_daylight_max + l2_bright /sys/class/backlight//l2_bright_max + l3_office /sys/class/backlight//l3_office_max + l4_indoor /sys/class/backlight//l4_indoor_max + l5_dark /sys/class/backlight//l5_dark_max + =========== ================================================ + + See also: /sys/class/backlight//ambient_light_zone. + +What: /sys/class/backlight//_dim +Date: Sep, 2009 +KernelVersion: v2.6.32 +Contact: device-drivers-devel@blackfin.uclinux.org +Description: + Control the dim brightness for + on this . Values are between 0 and 127, typically + set to 0. Full off when the backlight is disabled. + This file will also show the dim brightness level stored for + this . + + The is device-driver specific: + + For ADP5520 and ADP5501, can be: + + =========== ================================================ + Ambient sysfs entry + light zone + =========== ================================================ + daylight /sys/class/backlight//daylight_dim + office /sys/class/backlight//office_dim + dark /sys/class/backlight//dark_dim + =========== ================================================ + + For ADP8860, can be: + + =========== ================================================ + Ambient sysfs entry + light zone + =========== ================================================ + l1_daylight /sys/class/backlight//l1_daylight_dim + l2_office /sys/class/backlight//l2_office_dim + l3_dark /sys/class/backlight//l3_dark_dim + =========== ================================================ + + For ADP8870, can be: + + =========== ================================================ + Ambient sysfs entry + light zone + =========== ================================================ + l1_daylight /sys/class/backlight//l1_daylight_dim + l2_bright /sys/class/backlight//l2_bright_dim + l3_office /sys/class/backlight//l3_office_dim + l4_indoor /sys/class/backlight//l4_indoor_dim + l5_dark /sys/class/backlight//l5_dark_dim + =========== ================================================ + + See also: /sys/class/backlight//ambient_light_zone. + -- cgit v1.3.1