Re: Problem with backlight control and question about kernel information and patches

[Benjamin Cama <benoar@dolka.fr>]

Hi,

Bumping this quite old thread, but with a solution.

Le lundi 29 août 2011 à 09:45 +0200, Michel Dänzer a écrit :
> On Mon, 2011-08-29 at 01:52 +0100, Clea F. Rees wrote: 
> > uname info: 3.0.0-1-powerpc #1 Sun Jul 24 13:59:10 UTC 2011 ppc GNU/Linux
> > 
> > Machine is a 12" G4 Aluminium PowerBook with a 1.5 GHz processor and a
> > nvidia graphics card so I'm using the nouveau drivers.
> 
> Then it sounds like nouveau doesn't support backlight control on your
> PowerBook yet. Or maybe the kernel is just missing some build
> configuration. You should probably talk to the nouveau kernel
> developers.

I just remembered getting the backlight to work some time ago with
nouveau on my powerbook. I looked around and found this message from
Andy Wingo: http://lkml.org/lkml/2008/1/12/170

This is his code that I used at the time, available here:
http://wingolog.org/pub/nvbacklight-0.1.tar.bz2

To get it to work on a recent kernel, I had to use this patch:

diff --git a/nvbacklight.c b/nvbacklight.c
index 927d36b..1af10e0 100644
--- a/nvbacklight.c
+++ b/nvbacklight.c
@@ -178,7 +178,7 @@ static struct fb_info *nvbacklight_attach(struct pci_dev *pd)
        par->fpSyncs = NV_RD32(par->PRAMDAC, 0x0848) & 0x30000033;
 
        bd = backlight_device_register("nvbacklight", &pd->dev, par,
-                                      &nvidia_bl_ops);
+                                      &nvidia_bl_ops, NULL);
        if (IS_ERR(bd)) {
                printk(KERN_WARNING "nvbacklight: registration failed\n");
                goto bl_device_register_failed;


You'll have to install linux-headers-powerpc, but then a simple make and
insmod and it works nicely here.

Regards,
benjamin