diff options
author | Hans de Goede <hdegoede@redhat.com> | 2017-12-23 19:41:47 +0100 |
---|---|---|
committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2017-12-28 12:45:07 +0100 |
commit | 5928c281524fe451114e04f1dfa11246a37e859f (patch) | |
tree | c48be48727499c51cb4ede3ae85ab200c8a2d9b6 /drivers/acpi/acpi_video.c | |
parent | 464e1d5f23cca236b930ef068c328a64cab78fb1 (diff) | |
download | linux-5928c281524fe451114e04f1dfa11246a37e859f.tar.bz2 |
ACPI / video: Default lcd_only to true on Win8-ready and newer machines
We're seeing a lot of bogus backlight interfaces on newer machines without
a LCD such as desktops, servers and HDMI sticks. This causes userspace to
show a non-functional brightness slider in e.g. the GNOME3 system menu,
which is undesirable. And, in general, we should simply just not register
a non functional backlight interface.
Checking the LCD flag causes the bogus acpi_video backlight interfaces to
go away (on the machines this was tested on).
This change sets the lcd_only option by default on any machines which
are Win8-ready, to fix this.
This is not entirely without a risk of regressions, but video_detect.c
already prefers native-backlight interfaces over the acpi_video one
on Win8-ready machines, calling acpi_video_unregister_backlight() as soon
as a native interface shows up. This is done because the ACPI backlight
interface often is broken on Win8-ready machines, because win8 does not
seem to actually use it.
So in practice we already end up not registering the ACPI backlight
interface on (most) Win8-ready machines with a LCD panel, thus this
change does not change anything for (most) machines with a LCD panel
and on machines without a LCD panel we actually don't want to register
any backlight interfaces.
This has been tested on the following machines and fixes a bogus backlight
interface showing up there:
- Desktop with an Asrock B150M Pro4S/D3 m.b. using i5-6500 builtin gfx
- Intel Compute Stick STK1AW32SC
- Meegopad T08 HDMI stick
Bogus backlight interfaces have also been reported on:
- Desktop with Asus H87I-Plus m.b.
- Desktop with ASRock B75M-ITX m.b.
- Desktop with Gigabyte Z87-D3HP m.b.
- Dell PowerEdge T20 desktop
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1097436
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1133327
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1133329
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1133646
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/acpi/acpi_video.c')
-rw-r--r-- | drivers/acpi/acpi_video.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c index 0972ec0e2eb8..f53ccc680238 100644 --- a/drivers/acpi/acpi_video.c +++ b/drivers/acpi/acpi_video.c @@ -80,8 +80,8 @@ MODULE_PARM_DESC(report_key_events, static bool device_id_scheme = false; module_param(device_id_scheme, bool, 0444); -static bool only_lcd = false; -module_param(only_lcd, bool, 0444); +static int only_lcd = -1; +module_param(only_lcd, int, 0444); static int register_count; static DEFINE_MUTEX(register_count_mutex); @@ -2136,6 +2136,16 @@ int acpi_video_register(void) goto leave; } + /* + * We're seeing a lot of bogus backlight interfaces on newer machines + * without a LCD such as desktops, servers and HDMI sticks. Checking + * the lcd flag fixes this, so enable this on any machines which are + * win8 ready (where we also prefer the native backlight driver, so + * normally the acpi_video code should not register there anyways). + */ + if (only_lcd == -1) + only_lcd = acpi_osi_is_win8(); + dmi_check_system(video_dmi_table); ret = acpi_bus_register_driver(&acpi_video_bus); |