On Friday, December 22, 2017 1:34:37 PM CET Hans de Goede wrote: > 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. More 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 commit enables the lcd_only option by default on any machines which > are win8 ready, fixing this. > > This is not entirely without 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 commit > 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 > > BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1097436 > BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1133327 > BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1133329 > BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1133646 > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> > --- > drivers/acpi/acpi_video.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c > index 0972ec0e2eb8..a83239507041 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() ? 1 : 0; Why not: only_lcd = !!acpi_osi_is_win8(); > + > dmi_check_system(video_dmi_table); > > ret = acpi_bus_register_driver(&acpi_video_bus); > -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
