Re: Trying to generate ACPI events from software

[Angela Dalton <angela-VPOBD8XdS/WVc3sceRu5cw@public.gmane.org>]

This is for a special project and will not be a normal part of ACPI, but 
I need the ability to turn off the display
for my project to work.  So I guess I will need to write a handler for 
the video devices in the acpi driver?

Yu, Luming wrote:

>Do you want ACPI export a interface to user to shut off the LCD through command like:
>#echo -n 3  > /proc/acpi/display/LCD0
>I don't think there is such functionality in current ACPI implementation.
>Maybe you can try to write such a driver display. 
>But we should enhance the stability of ACPI core on various platform first.
>Anyway, the various attractive PM features are based on a stable ACPI core.
>
>Thanks,
>Luming
>
>
>
>-----Original Message-----
>From: Angela Dalton [mailto:angela-VPOBD8XdS/WVc3sceRu5cw@public.gmane.org]
>Sent: 2003?4?17? 21:36
>To: acpi-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
>Subject: [ACPI] Trying to generate ACPI events from software
>
>
>Hello,
>
>I apologize in advance for the lengthy message!
>
>I am working on a program in which I would like to control the video 
>device power state based on something other than a timeout (specifically 
>based on information from external sensors).  Unfortunately, I can't 
>seem to figure out how to turn off the LCD and backlight from the 
>program.  I can blank the screen using "xset dpms force off" but the 
>backlight remains on, and a subsequent "xset dpms force on" from my 
>program has no effect, I actually have to physically move the mouse or 
>press a key.  I also tried writing to the /dev/nvram locations that 
>change when the lid is closed or the special keys are pressed to switch 
>from LCD to CRT.  Apparently, the changes in the nvram values do not 
>directly cause the display state change.
>
>I have been looking through the ACPI driver source code and the ACPID 
>code as well as the APCI Specification.  I have not been able to figure 
>out how to generate an event from within my program to tell ACPI to shut 
>the LCD off on my ThinkPad.  Here is what I think I understand:
>
>1. Based on the ACPI Specification, there is a Notify(VGA, 0x80) call to 
>tell the OSPM when the user presses the hotkey (in my case, FnF7) for 
>switching monitor output.  The OSPM should call the _DSS method to set 
>the device state of the LCD and CRT devices.
>
>2. From looking through the driver code, I found a file evevent.c that 
>seems to handle General Purpose events such as the one I want to cause. 
> This code detects events like a power button event and dispatches it to 
>an installed handler.  There appear to be both fixed event handlers and 
>generic general purpose event handlers.  There are also notify handlers. 
> This is a confusing part of the code for me as far as what I need to 
>do.  Do I need to write a notify handler and a fixed event handler?  Is 
>there a general notify handler that will invoke a general purpose event 
>handler that I would write?
>
>3.  Finally, based on what I see in the ospm directory, there is code to 
>handle a variety of events.  I assume this would be where my handler 
>would go.  It seems like this is a rather large undertaking, based on 
>the code for the other devices.  
>
>My questions are:
>
>Am I on the right track or completely lost??  And is there is much 
>easier way to do this using the ACPID or OSPMD?  If so, can someone 
>please explain it to me?  One thought I had was if my program could 
>generate a lid event then it might shut off the display (but how would I 
>get it back on and how can I prevent other stuff from also occuring, 
>like a suspend or hibernate?)
>
>I appreciate any help I can get!
>
>Best Regards,
>Angela Dalton
>
>
>
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>




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