[PATCH] acer-wmi: Fix regression in backlight detection

[PATCH] acer-wmi: Fix regression in backlight detection

[Michael Spang]

Currently we disable the Acer WMI backlight device if there is no ACPI
backlight device. As a result, we end up with no backlight device at
all. We should instead disable it if there is an ACPI device, as the
other laptop drivers do. This regression was introduced in febf2d9.

Signed-off-by: Michael Spang <mspang@csclub.uwaterloo.ca>
---
 drivers/platform/x86/acer-wmi.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

Each laptop driver with backlight support got a similar change around
febf2d9. The changes to the other drivers look correct; see e.g. a598c82f
for a similar but correct change. The regression is also in 2.6.28.

diff --git a/drivers/platform/x86/acer-wmi.c b/drivers/platform/x86/acer-wmi.c
index 94c9f91..6bcca61 100644
--- a/drivers/platform/x86/acer-wmi.c
+++ b/drivers/platform/x86/acer-wmi.c
@@ -1297,7 +1297,7 @@ static int __init acer_wmi_init(void)
 
 	set_quirks();
 
-	if (!acpi_video_backlight_support() && has_cap(ACER_CAP_BRIGHTNESS)) {
+	if (acpi_video_backlight_support() && has_cap(ACER_CAP_BRIGHTNESS)) {
 		interface->capability &= ~ACER_CAP_BRIGHTNESS;
 		printk(ACER_INFO "Brightness must be controlled by "
 		       "generic video driver\n");
-- 
1.6.0.6

Re: [PATCH] acer-wmi: Fix regression in backlight detection

[Carlos Corbacho]

[Adding Len Brown & linux-acpi to CC]

> Currently we disable the Acer WMI backlight device if there is no ACPI
> backlight device. As a result, we end up with no backlight device at
> all. We should instead disable it if there is an ACPI device, as the
> other laptop drivers do. This regression was introduced in febf2d9.

An identical patch has already been submitted, I'm just waiting on Len to
apply it:

http://patchwork.kernel.org/patch/7223/

> Signed-off-by: Michael Spang <mspang@csclub.uwaterloo.ca>
> ---
>  drivers/platform/x86/acer-wmi.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
>
> Each laptop driver with backlight support got a similar change around
> febf2d9. The changes to the other drivers look correct; see e.g. a598c82f
> for a similar but correct change. The regression is also in 2.6.28.

This won't apply cleanly to 2.6.28 due to the move of acer-wmi from
drivers/misc to drivers/platform/x86, so we'd probably need another patch
for stable. However, that can't happen until the original patch gets
merged upstream.

-Carlos

> diff --git a/drivers/platform/x86/acer-wmi.c
> b/drivers/platform/x86/acer-wmi.c
> index 94c9f91..6bcca61 100644
> --- a/drivers/platform/x86/acer-wmi.c
> +++ b/drivers/platform/x86/acer-wmi.c
> @@ -1297,7 +1297,7 @@ static int __init acer_wmi_init(void)
>
>  	set_quirks();
>
> -	if (!acpi_video_backlight_support() && has_cap(ACER_CAP_BRIGHTNESS)) {
> +	if (acpi_video_backlight_support() && has_cap(ACER_CAP_BRIGHTNESS)) {
>  		interface->capability &= ~ACER_CAP_BRIGHTNESS;
>  		printk(ACER_INFO "Brightness must be controlled by "
>  		       "generic video driver\n");
> --
> 1.6.0.6
>
>


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