Re: Check for ACPI backlight support otherwise use vendor ACPI

Jonathan Woithe
2008-07-31T02:52:30Z

> > I'm trying to sort out the status of this myself. Is the expectation
> > that your patches *with* the IGD work from Matthew/Hong should mean that
> > Fujitsus implementing IGD should not need fujitsu-laptop in order to
> > provide working software backlight brightness control?
> I think so.

Ok.

> > Or shouldn't Matthew/Hong's patchset be necessary with your patch in
> > theory?
> Thomas' patch assigns the responsibility to acpi video driver or
> platform drivers when a laptop supports brightness/display switch both
> via ACPI video extension and vendor specific control methods.
>
> brightness/display switch via ACPI video driver sometimes doesn't work
> even if the ACPI control methods are available, and Matthew/Hong's patch
> fixes this problem, on platforms with intel integrated graphics cards.

I see.

> And now, we should root cause why acpi_video_backlight_support() failed
> on this laptop.

Agreed.

> > so allowing fujitsu-laptop to co-exist with video.ko handling the
> > backlight (as your patches allow) is the right thing to do.
>
> sure, they will co-exist, but I don't think fujitsu-laptop should handle
> the backlight stuff, unless it's explicitly stated via the boot
> parameter "ï»¿acpi_backlight=vendor".

For laptops with both ACPI video extensions and vendor specific control
methods I agree with this. However, users of laptops which have only vendor
specific control methods (of which the S7020 is one AFAIK) should not have
to give any boot parameters for things to work for them. In other words,
"acpi_backlight=vendor" should only come into play when the machine has the
ACPI video extensions. I am assuming that this is the intention since
that's what the current patches appear to do.

Is there a canonical source for Matthew/Hong's patch? To totally wrap this
up I would like to try the S7020 with Matthew/Hong+Thomas. I doubt
Matthew/Hong's work is relevant to the S7020 given that it's 3+ years old
now, but it's best to test these things early.

Regards
jonathan
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html