Re: [PATCH] laptop_panel.brightness_in_hardware: add all Asus laptops

Re: [PATCH] laptop_panel.brightness_in_hardware: add all Asus laptops

[Alan Jenkins]

Matthew Garrett wrote:
> The problem in that case is that the kernel changes the backlight for 
> us. The lack of consistency on this front makes life somewhat harder. 
>
> In terms of the "Some hardware sends keyboard events but also changes 
> the brightness", I'm working on a cleaner solution for this. The easiest 
> would seem to be to generate a uevent when the backlight is changed, 
> which would then allow userspace to pop up UI even though the key press 
> events aren't propagated. It would seem to deal with the Eee (and older 
> Thinkpad) cases quite nicely, but does require some more code in 
> userspace.
>   

Ok. Maybe it's trivial or "niche", but I really appreciate this. I think 
it's the only remaining issue I have with my EeePC :-).

I just saw the patch to generate uevents for the acpi video driver. It 
looks like it still generates KEY_BRIGHTNESSDOWN. Are you planning a 
followup patch, to suppress the input events when 
brightness_switch_enabled == 1?

Equally, w.r.t patch 3, I don't think eeepc-laptop, should generate 
brightness events on the *input* device anymore.

The rationale is that KEY_BRIGHTNESSDOWN is a user request to increase 
brightness. In these cases, the firmware/driver has already increased 
the brightness. We've notified userspace via the backlight device. So we 
shouldn't pass the request on to userspace; it has already been acted 
upon. If we still generate KEY_BRIGHTNESS*, userspace has to guess 
whether or not the change has already been applied. If there is too much 
latency, it guesses wrong :-(.

Thanks!
Alan

Re: [PATCH] laptop_panel.brightness_in_hardware: add all Asus laptops

[Matthew Garrett]

On Thu, Jul 16, 2009 at 11:22:47PM +0100, Alan Jenkins wrote:

> I just saw the patch to generate uevents for the acpi video driver. It  
> looks like it still generates KEY_BRIGHTNESSDOWN. Are you planning a  
> followup patch, to suppress the input events when  
> brightness_switch_enabled == 1?

I didn't want to change the behaviour of the driver with existing 
userspace, but yes, I agree that that's the correct behaviour. To make 
it consistent with everything else it should probably also default to 
brightness_switch_enabled = 0 (and we ship it that way in Fedora), but 
again, compatibility.

> Equally, w.r.t patch 3, I don't think eeepc-laptop, should generate  
> brightness events on the *input* device anymore.

Right.

> The rationale is that KEY_BRIGHTNESSDOWN is a user request to increase  
> brightness. In these cases, the firmware/driver has already increased  
> the brightness. We've notified userspace via the backlight device. So we  
> shouldn't pass the request on to userspace; it has already been acted  
> upon. If we still generate KEY_BRIGHTNESS*, userspace has to guess  
> whether or not the change has already been applied. If there is too much  
> latency, it guesses wrong :-(.

Absolutely. The other thing that needs doing is for dell-laptop to 
consume the brightness keys, or alternatively for us to remap them on 
Dells. Right now (in the worst case) we're getting two sets of them.

-- 
Matthew Garrett | mjg59@srcf.ucam.org