brightness of the screen at boot, kernel 3.11-2-686-pae

[Gerard ROBIN <g.robin3@free.fr>]

Hello
I run wheezy (Debian) on laptop aspire 5102 
I am trying the kernel 3.11-2-686-pae.
Everything works fine, but the screen brightness is maximum at boot while 
with the 3.10 kernel it is at the minimum.
Is it possible to boot with the minimum brightness with the kernel 3.11-2-686-pae ?
And how to do that ?

I notice that:
with the kernel 3.10-0.bpo.3-686-pae there is the directory :
/sys/class/backlight/acpi_video0$/acpi_video0

and with kernel 3.11-2-686-pae there are the directories:
/sys/class/backlight/acpi_video0$/acpi_video0
/sys/class/backlight/acpi_video0$/radeon_bl0

TIA

-- 
Gérard