From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ondrej Zajicek Subject: Framebuffer questions Date: Wed, 15 Mar 2006 22:10:22 +0100 Message-ID: <20060315211022.GA4474@localhost.localdomain> Reply-To: linux-fbdev-devel@lists.sourceforge.net Mime-Version: 1.0 Return-path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1FJdGI-00011k-T8 for linux-fbdev-devel@lists.sourceforge.net; Wed, 15 Mar 2006 13:10:30 -0800 Received: from smtp1.kolej.mff.cuni.cz ([195.113.24.4]) by mail.sourceforge.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.44) id 1FJdGH-0006Zf-7w for linux-fbdev-devel@lists.sourceforge.net; Wed, 15 Mar 2006 13:10:30 -0800 Received: from localhost.localdomain (feanorr.kolej.mff.cuni.cz [195.113.26.209]) by smtp1.kolej.mff.cuni.cz (8.13.4/8.13.1) with ESMTP id k2FLANgO042945 for ; Wed, 15 Mar 2006 22:10:25 +0100 (CET) (envelope-from zajio1am@artax.karlin.mff.cuni.cz) Received: from santiago by localhost.localdomain with local (Exim 4.50) id 1FJdGA-0001mQ-4c for linux-fbdev-devel@lists.sourceforge.net; Wed, 15 Mar 2006 22:10:22 +0100 Content-Disposition: inline Sender: linux-fbdev-devel-admin@lists.sourceforge.net Errors-To: linux-fbdev-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: List-Post: List-Help: List-Subscribe: , List-Archive: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-fbdev-devel@lists.sourceforge.net Hello I have several questions about fbdev. I already read FB-FAQ, most docs in Documentation/fb/*, linux/fb.h and some messages in archive of this mailing list. - I understood that if i want to change videomode then i should set all items in struct fb_var_screeninfo, call ioctl FBIOPUT_VSCREENINFO, driver considers wanted parameters and if exactly this mode or mode with more bits_per_pixel or greater some bitfield.length is supported, then mode is changed, otherwise change is rejected. If change is successfull, then i should call ioctl FBIOGET_VSCREENINFO and FBIOGET_FSCREENINFO to get information about real framebuffer structure. Is this correct? - Should i really set all fields? For example offset and msb_right parts of red, green, blue and transp. I usually don't care of this so i want to set some DONT_CARE value. Or are these items always ignored so i needn't set anything? - If i have to supply complete mode timings for videomode change why there is modedb.c and mode lines stored inside drivers? - I see there is FB_TYPE_TEXT mode (assume for standard text mode). what should i set in struct fb_var_screeninfo to get this mode? If i grep drivers/video for it, i get it occurs only in vga16fb. Is there some deep reason for this or just programmers of other fb drivers don't care about text mode? - Is there some possibility to get list of possible framebuffer videomodes? Or just list of possible 'structural' framebuffer configurations (type,visual,bpp,r/g/b)? (i hope that usually this is ortogonal to resolution and timings setting - suppose have enough ram). I know about FB_ACTIVATE_TEST but use iterative binary search to find all video modes isn't sane idea :-) - Is there description of fb sysfs interface anywhere? - Is there description of specific framebuffer formats for various FB_TYPE_* and FB_AUX_* anywhere? - I found that with vga16fb i can access just first plane. Is it possible to switch planes from userspace and without interaction with VGA registers? - What exactly is supposed to do FB_SYNC_BROADCAST ? - In include/fb.h there is: #define FB_VISUAL_PSEUDOCOLOR 3 /* Pseudo color (like atari) */ Is there some deep sense in remark '(like atari)' or is this well-known basic palette visual mode? I hope i can get some answers or hints. -- Elen sila lumenn' omentielvo Ondrej 'SanTiago' Zajicek (email: santiago@mail.cz, jabber: santiago@njs.netlab.cz) OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net) "To err is human -- to blame it on a computer is even more so." ------------------------------------------------------- This SF.Net email is sponsored by xPML, a groundbreaking scripting language that extends applications into web and mobile media. Attend the live webcast and join the prime developer group breaking into this new coding territory! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642