I reply to myself since noone answered the underlying question :
Is there any reason not to include the patch mentioned in my first mail into the mainline.
This patch is helping a lot in my case.

-----Message d'origine-----
De : BERNARD Sébastien [mailto:sebastien.bernard@fr.sfr.com]
Envoyé : mardi 30 mars 2004 16:47
À : 'acpi-devel@lists.sourceforge.net'
Objet : [ACPI] N800v is fixed by patch-1690

When trying to fix the new BIOS F18F provided by COMPAQ, I found some problem when executing the DSDT on boot which prevents the batteries from showing up.

When googling, I found this patch http://bugzilla.kernel.org/attachment.cgi?id=1690&action=view to fix the ECDT problem and It worked.

Could this patch be incorporated to the main line since it fixed all EVO nxxx  laptop (I think the BIOS is quite the same in those laptops).