Re: Strange effect with i915 backlight controller

From: Daniel Mack
Date: Mon Nov 07 2011 - 19:57:25 EST

Next message: Thomas Renninger: "Re: [PATCH -v2 0/4] ACPI: Re-factor and remove ./drivers/acpi/atomicio.[ch]"
Previous message: Thomas Renninger: "Re: [PATCH -v2 3/4] ACPI APEI: Convert atomicio routines"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Didn't get any response yet, hence copying LKML for a broader audience.

On 11/04/2011 03:36 PM, Daniel Mack wrote:

I'm facing a bug on a Samsung X20 notebook which features an i915
chipset (output of 'lspci -v' attached).

The effect is that setting the backlight to odd values causes the value
to be misinterpreted. Harald Hoyer (cc:) had the same thing on a Netbook
(I don't recall which model it was).

So this will turn the backlight to full brightness:

# cat /sys/class/backlight/intel_backlight/max_brightness
29750
# echo 29750 > /sys/class/backlight/intel_backlight/brightness

However, writing 29749 will turn the display backlight off, and 29748
appears to be the next valid lower value.

It seems like the IS_PINEVIEW() branch in
drivers/gpu/drm/i915/intel_panel.c:intel_panel_actually_set_backlight()
could do the right thing, but this code is written for an entirely
different model, right?

I can reproduce this on 3.0 and 3.1 vanilla as well as with the current
mainline git.

Let me know if there is any patch that I can test.

Thanks,
Daniel

00:00.0 Host bridge: Intel Corporation Mobile 915GM/PM/GMS/910GML Express Processor to DRAM Controller (rev 03)
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: bus master, fast devsel, latency 0
Capabilities: [e0] Vendor Specific Information: Len=09 <?>
Kernel driver in use: agpgart-intel

00:02.0 VGA compatible controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03) (prog-if 00 [VGA controller])
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: bus master, fast devsel, latency 0, IRQ 16
Memory at b0080000 (32-bit, non-prefetchable) [size=512K]
I/O ports at 1800 [size=8]
Memory at c0000000 (32-bit, prefetchable) [size=256M]
Memory at b0000000 (32-bit, non-prefetchable) [size=256K]
Expansion ROM at <unassigned> [disabled]
Capabilities: [d0] Power Management version 2
Kernel driver in use: i915
Kernel modules: intelfb, i915

00:02.1 Display controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03)
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: fast devsel
Memory at 42000000 (32-bit, non-prefetchable) [disabled] [size=512K]
Capabilities: [d0] Power Management version 2

00:1c.0 PCI bridge: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) PCI Express Port 1 (rev 03) (prog-if 00 [Normal decode])
Flags: bus master, fast devsel, latency 0
Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
I/O behind bridge: 00003000-00003fff
Memory behind bridge: b4000000-b7ffffff
Prefetchable memory behind bridge: 00000000d0000000-00000000d3ffffff
Capabilities: [40] Express Root Port (Slot+), MSI 00
Capabilities: [80] MSI: Enable+ Count=1/1 Maskable- 64bit-
Capabilities: [90] Subsystem: Samsung Electronics Co Ltd Device c01a
Capabilities: [a0] Power Management version 2
Capabilities: [100] Virtual Channel
Capabilities: [180] Root Complex Link
Kernel driver in use: pcieport
Kernel modules: shpchp

00:1d.0 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #1 (rev 03) (prog-if 00 [UHCI])
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: bus master, medium devsel, latency 0, IRQ 23
I/O ports at 1820 [size=32]
Kernel driver in use: uhci_hcd

00:1d.1 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #2 (rev 03) (prog-if 00 [UHCI])
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: bus master, medium devsel, latency 0, IRQ 19
I/O ports at 1840 [size=32]
Kernel driver in use: uhci_hcd

00:1d.2 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #3 (rev 03) (prog-if 00 [UHCI])
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: bus master, medium devsel, latency 0, IRQ 18
I/O ports at 1860 [size=32]
Kernel driver in use: uhci_hcd

00:1d.3 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #4 (rev 03) (prog-if 00 [UHCI])
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: bus master, medium devsel, latency 0, IRQ 16
I/O ports at 1880 [size=32]
Kernel driver in use: uhci_hcd

00:1d.7 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB2 EHCI Controller (rev 03) (prog-if 20 [EHCI])
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: bus master, medium devsel, latency 0, IRQ 23
Memory at b0040000 (32-bit, non-prefetchable) [size=1K]
Capabilities: [50] Power Management version 2
Capabilities: [58] Debug port: BAR=1 offset=00a0
Kernel driver in use: ehci_hcd

00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev d3) (prog-if 01 [Subtractive decode])
Flags: bus master, fast devsel, latency 0
Bus: primary=00, secondary=02, subordinate=06, sec-latency=32
I/O behind bridge: 00004000-00004fff
Memory behind bridge: b8000000-b80fffff
Prefetchable memory behind bridge: 0000000044000000-0000000049ffffff
Capabilities: [50] Subsystem: Gammagraphx, Inc. (or missing ID) Device 0000

00:1e.2 Multimedia audio controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) AC'97 Audio Controller (rev 03)
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: bus master, medium devsel, latency 0, IRQ 17
I/O ports at 1c00 [size=256]
I/O ports at 18c0 [size=64]
Memory at b0040800 (32-bit, non-prefetchable) [size=512]
Memory at b0040400 (32-bit, non-prefetchable) [size=256]
Capabilities: [50] Power Management version 2
Kernel driver in use: snd_intel8x0
Kernel modules: snd-intel8x0

00:1e.3 Modem: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) AC'97 Modem Controller (rev 03) (prog-if 00 [Generic])
Subsystem: Samsung Electronics Co Ltd Device 2115
Flags: medium devsel, IRQ 20
I/O ports at 2400 [size=256]
I/O ports at 2000 [size=128]
Capabilities: [50] Power Management version 2
Kernel modules: snd-intel8x0m

00:1f.0 ISA bridge: Intel Corporation 82801FBM (ICH6M) LPC Interface Bridge (rev 03)
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: bus master, medium devsel, latency 0
Kernel modules: iTCO_wdt, intel-rng

00:1f.1 IDE interface: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) IDE Controller (rev 03) (prog-if 8a [Master SecP PriP])
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: bus master, medium devsel, latency 0, IRQ 18
I/O ports at 01f0 [size=8]
I/O ports at 03f4 [size=1]
I/O ports at 0170 [size=8]
I/O ports at 0374 [size=1]
I/O ports at 1810 [size=16]
Kernel driver in use: ata_piix

00:1f.3 SMBus: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) SMBus Controller (rev 03)
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: medium devsel, IRQ 5
I/O ports at 18a0 [size=32]
Kernel modules: i2c-i801

02:05.0 Ethernet controller: Broadcom Corporation BCM4401-B0 100Base-TX (rev 02)
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: bus master, fast devsel, latency 32, IRQ 22
Memory at b8000000 (32-bit, non-prefetchable) [size=8K]
[virtual] Expansion ROM at 44000000 [disabled] [size=64K]
Capabilities: [40] Power Management version 2
Kernel driver in use: b44
Kernel modules: b44

02:07.0 Network controller: Intel Corporation PRO/Wireless 2200BG [Calexico2] Network Connection (rev 05)
Subsystem: Intel Corporation Samsung P35 integrated WLAN
Flags: bus master, medium devsel, latency 32, IRQ 20
Memory at b8002000 (32-bit, non-prefetchable) [size=4K]
Capabilities: [dc] Power Management version 2
Kernel driver in use: ipw2200
Kernel modules: ipw2200

02:09.0 CardBus bridge: Ricoh Co Ltd RL5c476 II (rev b3)
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: bus master, medium devsel, latency 168, IRQ 16
Memory at 000da000 (32-bit, non-prefetchable) [size=4K]
Bus: primary=02, secondary=03, subordinate=06, sec-latency=176
Memory window 0: 50000000-53fff000 (prefetchable)
Memory window 1: 4c000000-4ffff000
I/O window 0: 00004400-000044ff
I/O window 1: 00004000-000040ff
16-bit legacy interface ports at 0001
Kernel driver in use: yenta_cardbus
Kernel modules: yenta_socket

02:09.1 FireWire (IEEE 1394): Ricoh Co Ltd R5C552 IEEE 1394 Controller (rev 08) (prog-if 10 [OHCI])
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: bus master, medium devsel, latency 64, IRQ 17
Memory at b8003000 (32-bit, non-prefetchable) [size=2K]
Capabilities: [dc] Power Management version 2
Kernel driver in use: firewire_ohci
Kernel modules: firewire-ohci

02:09.2 SD Host controller: Ricoh Co Ltd R5C822 SD/SDIO/MMC/MS/MSPro Host Adapter (rev 17)
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: bus master, medium devsel, latency 32, IRQ 18
Memory at b8003800 (32-bit, non-prefetchable) [size=256]
Capabilities: [80] Power Management version 2
Kernel driver in use: sdhci-pci
Kernel modules: sdhci-pci

02:09.3 System peripheral: Ricoh Co Ltd R5C592 Memory Stick Bus Host Adapter (rev 08)
Subsystem: Samsung Electronics Co Ltd Device c01a
Flags: medium devsel, IRQ 255
Memory at b8003c00 (32-bit, non-prefetchable) [size=256]
Capabilities: [80] Power Management version 2

Next message: Thomas Renninger: "Re: [PATCH -v2 0/4] ACPI: Re-factor and remove ./drivers/acpi/atomicio.[ch]"
Previous message: Thomas Renninger: "Re: [PATCH -v2 3/4] ACPI APEI: Convert atomicio routines"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]