我在 sony vaio sve1511 笔记本电脑上遇到了一个有趣的问题。我发现在 linux 上（例如在最新的 ubuntu 16 上），我可以比在 windows 上调暗屏幕。为了演示这一点，我在 windows (10) 和 ubuntu (16) 上以最低亮度拍摄了两张照片。照片是在手动模式 1/20、1.8、iso 800 下拍摄的，正如您在 linux 上看到的，我可以将屏幕调暗更多...笔记本电脑有 ATI 7500/7600M 显卡。在 windows 10 上我有最新的驱动程序，我试过来自 sony 网站的旧驱动程序，但我无法将屏幕亮度调到 linux 上那么低。
问题是，Windows 上最小的屏幕亮度对我来说有点太多了 - 如果我可以让屏幕暗一点，对我的眼睛会更好。
一些 Linux 技术数据：
[ 6.310500] [drm] Initialized drm 1.1.0 20060810
[ 6.374350] [drm] radeon kernel modesetting enabled.
[ 6.387707] [drm] initializing kernel modesetting (TURKS 0x1002:0x6841 0x104D:0x90AB).
[ 6.387722] [drm] register mmio base: 0xC0000000
[ 6.387724] [drm] register mmio size: 131072
[ 6.387859] radeon 0000:01:00.0: VRAM: 1024M 0x0000000000000000 - 0x000000003FFFFFFF (1024M used)
[ 6.387862] radeon 0000:01:00.0: GTT: 1024M 0x0000000040000000 - 0x000000007FFFFFFF
[ 6.387865] [drm] Detected VRAM RAM=1024M, BAR=256M
[ 6.387867] [drm] RAM width 128bits DDR
[ 6.388037] [drm] radeon: 1024M of VRAM memory ready
[ 6.388039] [drm] radeon: 1024M of GTT memory ready.
[ 6.388059] [drm] Loading TURKS Microcode
[ 6.388180] [drm] Internal thermal controller without fan control
[ 6.390553] [drm] radeon: dpm initialized
[ 6.390684] [drm] GART: num cpu pages 262144, num gpu pages 262144
[ 6.391647] [drm] PCIE gen 2 link speeds already enabled
[ 6.401284] [drm] PCIE GART of 1024M enabled (table at 0x0000000000274000).
[ 6.401400] radeon 0000:01:00.0: WB enabled
[ 6.401405] radeon 0000:01:00.0: fence driver on ring 0 use gpu addr 0x0000000040000c00 and cpu addr 0xffff8800aae58c00
[ 6.401408] radeon 0000:01:00.0: fence driver on ring 3 use gpu addr 0x0000000040000c0c and cpu addr 0xffff8800aae58c0c
[ 6.401913] radeon 0000:01:00.0: fence driver on ring 5 use gpu addr 0x0000000000072118 and cpu addr 0xffffc90002032118
[ 6.401918] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[ 6.401919] [drm] Driver supports precise vblank timestamp query.
[ 6.401922] radeon 0000:01:00.0: radeon: MSI limited to 32-bit
[ 6.401957] radeon 0000:01:00.0: radeon: using MSI.
[ 6.401994] [drm] radeon: irq initialized.
[ 6.421516] [drm] ring test on 0 succeeded in 1 usecs
[ 6.421526] [drm] ring test on 3 succeeded in 3 usecs
[ 6.607648] [drm] ring test on 5 succeeded in 1 usecs
[ 6.607654] [drm] UVD initialized successfully.
[ 6.607938] [drm] ib test on ring 0 succeeded in 0 usecs
[ 6.607967] [drm] ib test on ring 3 succeeded in 0 usecs
[ 7.274388] [drm] ib test on ring 5 succeeded
[ 7.338243] [drm] radeon atom DIG backlight initialized
[ 7.338246] [drm] Radeon Display Connectors
[ 7.338247] [drm] Connector 0:
[ 7.338248] [drm] LVDS-1
[ 7.338250] [drm] DDC: 0x6560 0x6560 0x6564 0x6564 0x6568 0x6568 0x656c 0x656c
[ 7.338251] [drm] Encoders:
[ 7.338252] [drm] LCD1: INTERNAL_UNIPHY
[ 7.338253] [drm] Connector 1:
[ 7.338254] [drm] HDMI-A-1
[ 7.338255] [drm] HPD1
[ 7.338256] [drm] DDC: 0x6430 0x6430 0x6434 0x6434 0x6438 0x6438 0x643c 0x643c
[ 7.338257] [drm] Encoders:
[ 7.338258] [drm] DFP1: INTERNAL_UNIPHY1
[ 7.338259] [drm] Connector 2:
[ 7.338260] [drm] VGA-1
[ 7.338261] [drm] DDC: 0x64d8 0x64d8 0x64dc 0x64dc 0x64e0 0x64e0 0x64e4 0x64e4
[ 7.338262] [drm] Encoders:
[ 7.338263] [drm] CRT1: INTERNAL_KLDSCP_DAC1
[ 7.747335] [drm] fb mappable at 0xB0475000
[ 7.747338] [drm] vram apper at 0xB0000000
[ 7.747339] [drm] size 4325376
[ 7.747340] [drm] fb depth is 24
[ 7.747341] [drm] pitch is 5632
[ 7.747455] fbcon: radeondrmfb (fb0) is primary device
[ 8.341225] radeon 0000:01:00.0: fb0: radeondrmfb frame buffer device
[ 8.355116] [drm] Initialized radeon 2.43.0 20080528 for 0000:01:00.0 on minor 0
01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Thames [Radeon HD 7550M/7570M/7650M] [1002:6841]
*-display
description: VGA compatible controller
product: Thames [Radeon HD 7550M/7570M/7650M]
vendor: Advanced Micro Devices, Inc. [AMD/ATI]
physical id: 0
bus info: pci@0000:01:00.0
version: 00
width: 64 bits
clock: 33MHz
capabilities: pm pciexpress msi vga_controller bus_master cap_list rom
configuration: driver=radeon latency=0
resources: irq:29 memory:b0000000-bfffffff memory:c0000000-c001ffff ioport:3000(size=256) memory:c0040000-c005ffff
00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor Family DRAM Controller (rev 09)
Subsystem: Sony Corporation 2nd Generation Core Processor Family DRAM Controller
Flags: bus master, fast devsel, latency 0
Capabilities: <access denied>
00:01.0 PCI bridge: Intel Corporation Xeon E3-1200/2nd Generation Core Processor Family PCI Express Root Port (rev 09) (prog-if 00 [Normal decode])
Flags: bus master, fast devsel, latency 0, IRQ 24
Bus: primary=00, secondary=01, subordinate=06, sec-latency=0
I/O behind bridge: 00003000-00003fff
Memory behind bridge: c0000000-c0ffffff
Prefetchable memory behind bridge: 00000000b0000000-00000000bfffffff
Capabilities: <access denied>
Kernel driver in use: pcieport
Kernel modules: shpchp
00:14.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB xHCI Host Controller (rev 04) (prog-if 30 [XHCI])
Subsystem: Sony Corporation 7 Series/C210 Series Chipset Family USB xHCI Host Controller
Flags: bus master, medium devsel, latency 0, IRQ 25
Memory at c1300000 (64-bit, non-prefetchable) [size=64K]
Capabilities: <access denied>
Kernel driver in use: xhci_hcd
00:1a.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller #2 (rev 04) (prog-if 20 [EHCI])
Subsystem: Sony Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller
Flags: bus master, medium devsel, latency 0, IRQ 16
Memory at c1318000 (32-bit, non-prefetchable) [size=1K]
Capabilities: <access denied>
Kernel driver in use: ehci-pci
00:1b.0 Audio device: Intel Corporation 7 Series/C210 Series Chipset Family High Definition Audio Controller (rev 04)
Subsystem: Sony Corporation 7 Series/C210 Series Chipset Family High Definition Audio Controller
Flags: bus master, fast devsel, latency 0, IRQ 30
Memory at c1310000 (64-bit, non-prefetchable) [size=16K]
Capabilities: <access denied>
Kernel driver in use: snd_hda_intel
Kernel modules: snd_hda_intel
00:1c.0 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 1 (rev c4) (prog-if 00 [Normal decode])
Flags: bus master, fast devsel, latency 0, IRQ 17
Bus: primary=00, secondary=07, subordinate=07, sec-latency=0
Memory behind bridge: c1200000-c12fffff
Capabilities: <access denied>
Kernel driver in use: pcieport
Kernel modules: shpchp
00:1c.1 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 2 (rev c4) (prog-if 00 [Normal decode])
Flags: bus master, fast devsel, latency 0, IRQ 16
Bus: primary=00, secondary=08, subordinate=08, sec-latency=0
Memory behind bridge: c1100000-c11fffff
Capabilities: <access denied>
Kernel driver in use: pcieport
Kernel modules: shpchp
00:1c.2 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 3 (rev c4) (prog-if 00 [Normal decode])
Flags: bus master, fast devsel, latency 0, IRQ 18
Bus: primary=00, secondary=09, subordinate=09, sec-latency=0
I/O behind bridge: 00002000-00002fff
Prefetchable memory behind bridge: 00000000c1000000-00000000c10fffff
Capabilities: <access denied>
Kernel driver in use: pcieport
Kernel modules: shpchp
00:1d.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller #1 (rev 04) (prog-if 20 [EHCI])
Subsystem: Sony Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller
Flags: bus master, medium devsel, latency 0, IRQ 23
Memory at c1317000 (32-bit, non-prefetchable) [size=1K]
Capabilities: <access denied>
Kernel driver in use: ehci-pci
00:1f.0 ISA bridge: Intel Corporation HM76 Express Chipset LPC Controller (rev 04)
Subsystem: Sony Corporation HM76 Express Chipset LPC Controller
Flags: bus master, medium devsel, latency 0
Capabilities: <access denied>
Kernel driver in use: lpc_ich
Kernel modules: lpc_ich
00:1f.2 SATA controller: Intel Corporation 7 Series Chipset Family 6-port SATA Controller [AHCI mode] (rev 04) (prog-if 01 [AHCI 1.0])
Subsystem: Sony Corporation 7 Series Chipset Family 6-port SATA Controller [AHCI mode]
Flags: bus master, 66MHz, medium devsel, latency 0, IRQ 26
I/O ports at 4048 [size=8]
I/O ports at 4054 [size=4]
I/O ports at 4040 [size=8]
I/O ports at 4050 [size=4]
I/O ports at 4020 [size=32]
Memory at c1316000 (32-bit, non-prefetchable) [size=2K]
Capabilities: <access denied>
Kernel driver in use: ahci
Kernel modules: ahci
00:1f.3 SMBus: Intel Corporation 7 Series/C210 Series Chipset Family SMBus Controller (rev 04)
Subsystem: Sony Corporation 7 Series/C210 Series Chipset Family SMBus Controller
Flags: medium devsel, IRQ 10
Memory at c1314000 (64-bit, non-prefetchable) [size=256]
I/O ports at 4000 [size=32]
Kernel modules: i2c_i801
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Thames [Radeon HD 7550M/7570M/7650M] (prog-if 00 [VGA controller])
Subsystem: Sony Corporation Thames [Radeon HD 7550M/7570M/7650M]
Flags: bus master, fast devsel, latency 0, IRQ 29
Memory at b0000000 (64-bit, prefetchable) [size=256M]
Memory at c0000000 (64-bit, non-prefetchable) [size=128K]
I/O ports at 3000 [size=256]
Expansion ROM at c0040000 [disabled] [size=128K]
Capabilities: <access denied>
Kernel driver in use: radeon
Kernel modules: radeon
01:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Turks/Whistler HDMI Audio [Radeon HD 6000 Series]
Subsystem: Sony Corporation Turks/Whistler HDMI Audio [Radeon HD 6000 Series]
Flags: bus master, fast devsel, latency 0, IRQ 31
Memory at c0020000 (64-bit, non-prefetchable) [size=16K]
Capabilities: <access denied>
Kernel driver in use: snd_hda_intel
Kernel modules: snd_hda_intel
07:00.0 Network controller: Qualcomm Atheros AR9485 Wireless Network Adapter (rev 01)
Subsystem: Foxconn International, Inc. Unex DHXA-225
Flags: bus master, fast devsel, latency 0, IRQ 16
Memory at c1200000 (64-bit, non-prefetchable) [size=512K]
Expansion ROM at c1280000 [disabled] [size=64K]
Capabilities: <access denied>
Kernel driver in use: ath9k
Kernel modules: ath9k
08:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS5209 PCI Express Card Reader (rev 01)
Subsystem: Sony Corporation RTS5209 PCI Express Card Reader
Flags: bus master, fast devsel, latency 0, IRQ 27
Memory at c1100000 (32-bit, non-prefetchable) [size=4K]
Capabilities: <access denied>
Kernel driver in use: rtsx_pci
Kernel modules: rtsx_pci
09:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 07)
Subsystem: Device 90ab:104d
Flags: bus master, fast devsel, latency 0, IRQ 28
I/O ports at 2000 [size=256]
Memory at c1004000 (64-bit, prefetchable) [size=4K]
Memory at c1000000 (64-bit, prefetchable) [size=16K]
Capabilities: <access denied>
Kernel driver in use: r8169
Kernel modules: r8169
01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Thames [Radeon HD 7550M/7570M/7650M] [1002:6841]
Subsystem: Sony Corporation Thames [Radeon HD 7550M/7570M/7650M] [104d:90ab]
Kernel driver in use: radeon
Kernel modules: radeon