From: "Frank Murphy" <murphyf+xfree86@f-m•fm>
To: "Benjamin Herrenschmidt" <benh@kernel•crashing.org>,
"Frank Murphy" <murphyf+xfree86@f-m•fm>
Cc: debian-x@lists•debian.org, linuxppc-dev list <linuxppc-dev@ozlabs•org>
Subject: Re: G3 iBook LCD brightness in X under kernel 2.4.25 and 2.6.8
Date: Mon, 29 Nov 2004 10:42:35 +0100 [thread overview]
Message-ID: <1101721355.31317.209633721@webmail.messagingengine.com> (raw)
In-Reply-To: <1101674379.4653.9.camel@gaston>
On Mon, 29 Nov 2004 07:39:39 +1100, "Benjamin Herrenschmidt" said:
> On Sun, 2004-11-28 at 21:14 +0100, Frank Murphy wrote:
> > On Sunday 28 November 2004 2:58, Benjamin Herrenschmidt wrote:
> > > >
> > > > So I've tried this using the stock Debian 2.6.8 and 2.6.9 PPC kernels
> > > > with the same results.
> > > >
> > > > $ grep ATY /boot/config-2.6.9-powerpc
> > > > CONFIG_FB_ATY128=y
> > > > CONFIG_FB_ATY=y
> > > > CONFIG_FB_ATY_CT=y
> > > > CONFIG_FB_ATY_GX=y
> > > > # CONFIG_FB_ATY_XL_INIT is not set
> > > >
> > > > It seems that the atyfb module is compiled in. Is there another way to
> > > > check?
> > >
> > > Check the bits in CONFIG_PMAC_BACKLIGHT in atyfb (like, add some
> > > printk's to see if they are reached etc..)
> >
> > So I added a couple of printk()s like you asked. I added one to
> > aty128fb_blank() in aty128fb.c:2037 and two to aty_init() in
> > atyfb_base.c:1793 and 1802 (inside the 'if (M64_HAS(MOBIL_BUS))'). The one I
> > added to aty128fb didn't print (as expected), but both of them from
> > atyfb_base.c printed. So it seems that CONFIG_PMAC_BACKLIGHT is properly
> > defined. Anything you'd specifically like me to try?
>
> Well, the backlight control is done by writing to one of the LCD
> register, you can try to track down the values in there and eventually
> compare with 2.4
I'll try to look at this, but I don't know very much about it.
> > I find it interesting that in the console the dimming works. I thought that on
> > PPC the console used the framebuffer. Another notable thing is that while in
> > X, the dimming doesn't work, but when I switch to one of the VTs, the screen
> > brightness is adjusted to what it should have been in X.
>
> Ah ? What do you mean by "dimming" ? blanking ? or backlight control ?
OK, the F1 and F2 keys on my keyboard have little "brighter"/"dimmer"
icons on them. When I press them when running X on 2.4.25, the screen
brightness changes. So for me, that's "dimming." I believe that it's the
"backlight control" that does this. When I press the "dimmer" button
enough (8 times, I think), then the backlight turns totally off, and I
can't see anything on the screen. For me that's "blanking" in this
context. It's true that something else (X, I think) will kind of blank
the screen, but the backlight stays lit. I noticed this when I closed
the lid to make the iBook sleep, but the backlight stayed on, warming
the keyboard. I then noticed the same problem with the dimmer keys.
> Could be some crap done by the X driver ... It's notoriously allergic to
> fbdev's ... I'll have to double check.
It probably is. But it's strange because I use all the same software
except the kernel to get this behavior. So there's something with the
kernel / X interface that has changed, either for 2.6 or the way Debian
builds 2.6. I have a hard time with this because there are so many
interactions: is it the PMU? The APM emulation? X driver? Kernel
driver? I don't have a good idea about how these things interact.
Let me know what you find out.
Frank
next prev parent reply other threads:[~2004-11-29 9:42 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200411232008.16854.murphyf+xfree86@f-m.fm>
2004-11-26 10:28 ` G3 iBook LCD brightness in X under kernel 2.4.25 and 2.6.8 Christof Petig
2004-11-26 15:38 ` murphyf+xfree86
2004-11-27 1:02 ` Benjamin Herrenschmidt
2004-11-27 8:48 ` Frank Murphy
2004-11-28 1:58 ` Benjamin Herrenschmidt
2004-11-28 20:14 ` Frank Murphy
2004-11-28 20:39 ` Benjamin Herrenschmidt
2004-11-29 9:42 ` Frank Murphy [this message]
2004-11-29 17:17 ` Christof Petig
2004-11-30 8:02 ` Christof Petig
2004-11-30 9:05 ` Frank Murphy
2004-12-01 8:25 ` murphyf+xfree86
2004-11-29 21:56 ` Benjamin Herrenschmidt
2004-11-29 0:45 ` Christof Petig
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