Re: [PATCH v2 2/3] acer-wmi: Switch to acpi_video_unregister_backlight

[joeyli <jlee@suse.com>]

On Sat, May 17, 2014 at 10:48:02AM +0200, Hans de Goede wrote:
> Switch from acpi_video_unregister(), to acpi_video_unregister_backlight(),
> so that the hotkeys handler registered by acpi-video stays in place.
> 
> Since there are no mappings for the atkbd raw codes for the brightness
> keys used by newer Acer models in /lib/udev/hwdb.d/60-keyboard.hwdb, and
> since we map the wmi events with a code of KE_IGNORE, we rely on acpi-video
> to do the hotkey handling for us.
> 
> For laptops such as the Acer Aspire 5750 which uses intel gfx this works
> despite us calling acpi_video_unregister() because the following happens:
> 
> 1) acpi-video module gets loaded (as it is a dependency of acer-wmi and i915)
> 2) acpi-video does NOT call acpi_video_register()
> 3) acer-wmi loads (assume it loads before i915), calls
> acpi_video_dmi_promote_vendor(); which sets ACPI_VIDEO_BACKLIGHT_DMI_VENDOR
> 4) calls acpi_video_unregister -> not registered, nop
> 5) i915 loads, calls acpi_video_register
> 6) acpi_video_register registers the acpi_notifier for the hotkeys,
>    does NOT register a backlight device because of ACPI_VIDEO_BACKLIGHT_DMI_VENDOR
> 
> But on the Acer Aspire 5750G, which uses nvidia graphics the following happens:
> 1) acpi-video module gets loaded (as it is a dependency of acer-wmi)
> 2) acpi-video calls acpi_video_register()
> 3) acpi_video_register registers the acpi_notifier for the hotkeys,
>    and a backlight device
> 4) acer-wmi loads, calls acpi_video_dmi_promote_vendor()
> 5) calls acpi_video_unregister, this unregisters BOTH the acpi_notifier for
>    the hotkeys AND the backlight device
> 
> And we end up without any handler for the brightness hotkeys. This patch fixes
> this by switching over to acpi_video_unregister_backlight() which keeps the
> hotkey handler in place.
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=35622
> 
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>

This patch is good to me.

Reviewd-by: Lee, Chun-Yi <jlee@suse.com>


Thanks for your patch.

> ---
>  drivers/platform/x86/acer-wmi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/platform/x86/acer-wmi.c b/drivers/platform/x86/acer-wmi.c
> index c91f69b3..3a74699 100644
> --- a/drivers/platform/x86/acer-wmi.c
> +++ b/drivers/platform/x86/acer-wmi.c
> @@ -2228,7 +2228,7 @@ static int __init acer_wmi_init(void)
>  		pr_info("Brightness must be controlled by acpi video driver\n");
>  	} else {
>  		pr_info("Disabling ACPI video driver\n");
> -		acpi_video_unregister();
> +		acpi_video_unregister_backlight();
>  	}
>  
>  	if (wmi_has_guid(WMID_GUID3)) {
> -- 
> 1.9.0
> 

Joey Lee