Re: [PATCH] ACPI video: Don't export sysfs backlight interface if query _BCL fail

["Luming Yu" <luming.yu@gmail.com>]

Ack!


On 4/27/07, Danny Kukawka <dkukawka@suse.de> wrote:
> Hi,
>
> currently the acpi video module export the backlight interface to sysfs also
> if acpi_video_device_lcd_query_levels() fails to read _BLC method (e.g.
> because the method is not available). In this case the userspace don't know
> which brightness level are supported and can't set a brightness level (echo
> return with: "write error: Invalid Argument"). This happend e.g. on a ASUS
> RF1 (correct supported by the asus-laptop module).
>
> The video module should not export the backlight interface if query _BLC fail,
> because you can't set anything from userspace and this make it useless.
>
> See also: http://bugzilla.kernel.org/show_bug.cgi?id=8375
>
> Danny
>
> From: Danny Kukawka <dkukawka@suse.de>
> Subject: ACPI video: Don't export sysfs backlight interface if query _BLC fail
>
> if qeuery _BCL fail (e.g. because the method is missing in BIOS) don't
> export the backlight interface to sysfs.
>
> Signed-off-by: Danny Kukawka <dkukawka@suse.de>
> ---
>  video.c |   78 ++++++++++++++++++++++++++++--------------------------
>  1 file changed, 41 insertions(+), 37 deletions(-)
>
> --- linux-2.6.21/drivers/acpi/video.c   2007-04-26 13:50:51.000000000 +0200
> +++ linux-2.6.21/drivers/acpi/video.c   2007-04-26 13:50:53.000000000 +0200
> @@ -531,7 +531,6 @@