On Tuesday, September 30, 2014 02:10:17 PM Aaron Lu wrote: > The _DOD method lists which video output device is currently attached so > we should only care about them and ignore others. An user recently > reported that there are two acpi_video interfaces appeared on his system > and one of them doesn't work. From the acpidump, it is found that there > are more than one video output devices that have _BCM control method but > the _DOD lists only one of them. So this patch checks if the video output > device is in the _DOD list and will not create backlight device if it is > not in the list. Also, we consider the broken _DOD case(reflected by the > video->attached_count is 0) and do not change behaviour for those broken > _DOD systems. > > Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=84111 > Reported-and-tested-by: ntrrgc@xxxxxxxxx > Signed-off-by: Aaron Lu <aaron.lu@xxxxxxxxx> This looks reasonable to me, but I'm a little afraid that it may break systems which forget to list valid interfaces in the _DOD. For this reason, I'm queuing this up for 3.18, but not for -stable. We can request a backport after a while when we're reasonably sure that there are no regressions resulting from this. > --- > drivers/acpi/video.c | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c > index 7285c7f9a935..807a88a0f394 100644 > --- a/drivers/acpi/video.c > +++ b/drivers/acpi/video.c > @@ -1154,6 +1154,23 @@ acpi_video_device_bind(struct acpi_video_bus *video, > } > } > > +static bool acpi_video_device_in_dod(struct acpi_video_device *device) > +{ > + struct acpi_video_bus *video = device->video; > + int i; > + > + /* If we have a broken _DOD, no need to test */ > + if (!video->attached_count) > + return true; > + > + for (i = 0; i < video->attached_count; i++) { > + if (video->attached_array[i].bind_info == device) > + return true; > + } > + > + return false; > +} > + > /* > * Arg: > * video : video bus device > @@ -1593,6 +1610,15 @@ static void acpi_video_dev_register_backlight(struct acpi_video_device *device) > static int count; > char *name; > > + /* > + * Do not create backlight device for video output > + * device that is not in the enumerated list. > + */ > + if (!acpi_video_device_in_dod(device)) { > + dev_dbg(&device->dev->dev, "not in _DOD list, ignore\n"); > + return; > + } > + > result = acpi_video_init_brightness(device); > if (result) > return; > -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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
