From owner-freebsd-current Thu Nov 4 5: 5:59 1999 Delivered-To: freebsd-current@freebsd.org Received: from outmail.utsunomiya-u.ac.jp (outmail.utsunomiya-u.ac.jp [160.12.196.3]) by hub.freebsd.org (Postfix) with ESMTP id 8A220156FC for ; Thu, 4 Nov 1999 05:05:55 -0800 (PST) (envelope-from yokota@zodiac.mech.utsunomiya-u.ac.jp) Received: from zodiac.mech.utsunomiya-u.ac.jp (IDENT:A1Yb3W2MhArt90/l8sW++PCe561mA91+@zodiac.mech.utsunomiya-u.ac.jp [160.12.42.1]) by outmail.utsunomiya-u.ac.jp (8.9.3/3.7Wpl2) with ESMTP id WAA29919; Thu, 4 Nov 1999 22:04:23 +0900 (JST) Received: from zodiac.mech.utsunomiya-u.ac.jp (zodiac.mech.utsunomiya-u.ac.jp [160.12.42.1]) by zodiac.mech.utsunomiya-u.ac.jp (8.7.6+2.6Wbeta7/3.4W/zodiac-May96) with ESMTP id WAA16201; Thu, 4 Nov 1999 22:08:57 +0900 (JST) Message-Id: <199911041308.WAA16201@zodiac.mech.utsunomiya-u.ac.jp> To: Amancio Hasty Cc: current@freebsd.org, yokota@zodiac.mech.utsunomiya-u.ac.jp Subject: Re: vga driver and signal In-reply-to: Your message of "Wed, 03 Nov 1999 14:23:15 PST." <199911032223.OAA39942@rah.star-gate.com> References: <199911032223.OAA39942@rah.star-gate.com> Date: Thu, 04 Nov 1999 22:08:56 +0900 From: Kazutaka YOKOTA Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG AFAIK, not all video cards generate the vertical retrace interrupt. Even worse, some BIOSes have a configuration option which instract the BIOS NOT to assign an IRQ to the PCI video card. I fully agree that the vertical retrace interrupt will be of great value, but I wonder if it is really worth the trouble, because it might be available in only few cards and systems at the end of the day... Well, I may be wrong :-) Kazu >Say is there anyone that can add signal delivery to the /sys/dev/fb/vga.c? >(For now any quick hack to the driver for delivering the signal will do ) > >The context is from a posting to the xfree86 mailing list: > > >keithp@suse.com said: >> You need to fit one event in per retrace. If you knew >> the phase of the sampling clock with respect to the retrace >> you could do that by skipping one sample then two then one, etc... >> But we don't know the phase and if you do that with >> arbitrary phase you end up sending two events in one retrace >> and then skipping the next and it looks worse. >> If we had a signal delivered at vertical retrace time, we could easily >> sync the mouse rate with the video rate -- run the mouse events >> through a simple filter and estimate mouse position at the vertical >> retrace interval using some forward estimation. > >> Additionally, the vertical retrace signal could be used for the double >> buffering extension to avoid tearing, and for the sync extension which >> kinda wants this. And for many video cards which can't update >> colormaps or cursor positions at other times without visible artifacts >> on the screen. > >> It would take some kernel work though; the results might well be worth >> the effort. > >> -keith > >I am too busy nowdays working :( To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message