On Friday 24 August 2007 00:12, Matthew Garrett wrote: > On Fri, Aug 24, 2007 at 11:55:41AM +0800, Zhang Rui wrote: > > > I have the same question for ACPI video driver. > > Take KEY_BRIGHTNESSUP/KEY_BRIGHTNESSDOWN for example, if ACPI video > > driver gets such a notification, it will change the brightness level > > first and then send an event to user space. > > The X people would prefer that the kernel not change the brightness > itself, where possible. In the cases where drivers know how to control > the backlight hardware themselves (most new Intel hardware, nvidia stuff > since 2005ish, that sort of thing) it's likely that they'll be able to > provide much more control than the level provided via the ACPI > interface. > > > I'll send a patch to make ACPI video driver do nothing but export the > > events to user space in the notify handler if you guys think it's okay. > > I think that's the right thing to do, but you might want to make it a > module option to begin with. That way you can printk that the behaviour > will change in the future, and then flip the default in a few months. We must handle two modes: 1. VGA mode, no X Control the video in the kernel via ACPI methods to talk to the BIOS. This is known to work on multiple laptops today. I don't see the utility in sending the hotkey events to user-space in this mode, but I also don't see the harm, so lets keep them as an FYI in case some graphics software doesn't know how to control the video but wants the event to re-probe or something. 2. Graphics mode, X is running While sometimes programming the video behind X's back using the kernel and BIOS ACPI entry points works, this is generally a bad idea. Here we need to disable the ACPI entry points that control video, and do nothing but send the input events to user-space to be picked up by the X server. Clearly there needs to be a mode bit. The mode bit should default to case #1 -- as that is what we are running today -- and when X knows to look for the input events and has the ability to switch modes natively, it should set the mode bit to switch us to case #2. The mode bit should probably live in the CONFIG_VIDEO_OUTPUT_CONTROL, eg. under driers/video/output.c with some generic name that in this case the acpi video driver registers for. Rui, can you follow up on this? thanks, -Len - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
