Thread (14 messages) 14 messages, 6 authors, 2007-03-01

Re: no backlight on radeon after recent kernel "upgrade"s

From: Richard Purdie <hidden>
Date: 2007-02-22 00:35:00
Also in: lkml

On Wed, 2007-02-21 at 00:56 -0500, Yaroslav Halchenko wrote:
I didn't mention 2.6.20-mm1 and got to see -mm2 so it is the one which
Iv'e tried, but, once again, I experienced the same issue with 19-mm?
kernels.

I built 2.6.20-mm2 without backlight support
$> grep BACKLIGH /boot/config-2.6.20-mm2 
# CONFIG_BACKLIGHT_LCD_SUPPORT is not set
# CONFIG_FB_BACKLIGHT is not set
# CONFIG_FB_RIVA_BACKLIGHT is not set
# CONFIG_FB_RADEON_BACKLIGHT is not set

that "eliminated" the problem. Also I can see the screen with pure
2.6.20 with backlight support (whatever it does since after
loading lcd, backlight modules, my /sys/class/{lcd,backlight} are empty):

*$> grep BACKLIGH /boot/config-2.6.20 
# CONFIG_FB_BACKLIGHT is not set
CONFIG_BACKLIGHT_LCD_SUPPORT=y
CONFIG_BACKLIGHT_CLASS_DEVICE=m
CONFIG_BACKLIGHT_DEVICE=y

quoted
Also, do you normally see files under /sys/class/lcd?
nope... after I load lcd module, no files under :-/ regardless either it
is mm or not. But there are files under /sys/class/backlight/ for mm2
compiled with backlight support (whenever the screen is dark as per my
original email)
There should be no files appearing under /sys/class/lcd, so thats all
normal. There is another report with similar symptoms which also sounds
like enabling the following options are at fault:

# CONFIG_FB_RIVA_BACKLIGHT is not set
# CONFIG_FB_RADEON_BACKLIGHT is not set

I suspect these options only work on certain hardware and aren't
generic. James, any idea what hardware these do/don't work with?

Worst case, we set them to depend on PMAC_BACKLIGHT again I guess...

Richard



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