From: erik quanstrom <quanstro@quanstro.net>
To: 9fans@9fans.net
Subject: Re: [9fans] aux/vga hsync/hblank confustion
Date: Wed, 14 Jan 2015 21:21:58 -0800 [thread overview]
Message-ID: <ede2d0798558d31dc68c90626ec58989@brasstown> (raw)
In-Reply-To: <581cb553c4f0794103d1444a810602cd@felloff.net>
> there are some vgadb entries that specify shs *smaller* than shb and the
> edid parser does the following:
>
> m->x = ha;
> m->ht = ha+hb;
> m->shs = ha; <- *WHAT*
> m->shb = ha+hso; <- *WHAT*
> m->ehb = ha+hso+hspw; <- *WHAT*
> m->ehs = ha+hb; <- *WHAT*
>
> where:
>
> ha = horizontal active
> hb = horizontal blanking
> hso = horizontal sync pulse offset (relative to start of blank)
> hspw = horisontal sync pulse width
>
> the hardcoded vesa standard modes in vesadb.c seem to use the field
> in the right way i think.
>
> interestinly, shs and ehb are rarely given in vgadb and we default
> to: shs = shb and ehs = ehb when omited, so this might explain why
> stuff works at all.
>
> so what is going on here?
this might explain some frustration i had years ago with getting timings correct.
- erik
prev parent reply other threads:[~2015-01-15 5:21 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-10 22:50 cinap_lenrek
2015-01-11 8:25 ` kokamoto
2015-01-15 5:21 ` erik quanstrom [this message]
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