Re: [PATCH 2/2] ACPI Check for backlight support via ACPI video.ko otherwise use vendor ACPI drivers

Matthew Garrett
2008-07-10T11:53:22Z

On Thu, Jul 10, 2008 at 01:36:04PM +0200, Thomas Renninger wrote:
> On Thursday 10 July 2008 13:19:00 Matthew Garrett wrote:
> > No, I said that on Thinkpads with a PWM method, the PWM method has to be
> > called in order to avoid the delay. There's no need for a blacklist.
>
> Ok.
> I just got a report that Dells must not use the video driver:
> https://bugzilla.novell.com/show_bug.cgi?id=404627
>
> They have a really ugly dcdbas driver which issues SMIs triggered from
> userspace.

If the ACPI video driver has bound, then using the dcdbas mechanism for
backlight control is incorrect. I wasn't aware that any Dells actually
implemented that. The correct thing is for userspace to stop using
dcdbas if a real backlight control is available, not to cripple the
ACPI video driver.