From owner-freebsd-hackers  Thu Apr  8  7:13:15 1999
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Date: Thu, 08 Apr 1999 07:08:08 -0600
From: Wes Peters <wes@softweyr.com>
Organization: Softweyr LLC
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To: Roger Hardiman <roger@cs.strath.ac.uk>
Cc: hackers@FreeBSD.ORG, multimedia@FreeBSD.ORG
Subject: Re: Bt848 corruption since upgrading to 3.1. Has DMA code changed?
References: <370CB2DC.709E7CEA@cs.strath.ac.uk>
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Roger Hardiman wrote:
> 
> Hi,
> 
> Several people (including Luigi) have reported that video capture with
> the bt848 driver is not working right since they upgraded from 2.2.6 or
> 2.2.8 to 3.1-release
> 
> Luigi and I noticed the problem in VIC (lots of horizontal lines in the
> image) and others have rpeorted FXTV problems.
> 
> It looks like a DMA problem. The DMA is either timing out or the bus
> mastering is failing or the DMA transfer data is getting corrupted.
> 
> Nothing has changed in the bt848 driver in this area since 2.2.x and I
> tested with the vic from 2.2.6 a.out format pkg_add.
> It looks like something has changed in the kernel's PCI bus setup code.
> 
> 
> Does anyone know what is different in the 3.x kernel (compared to the
> 2.2.x kernel) which could be causing this corruption.

Does the driver explicitly turn on PCI bus mastering on the card?  The
PCI initialization code no longer does this.  This change bit the fxp
driver on some machines where the BIOS doesn't initialize bus mastering
on the card.

-- 
       "Where am I, and what am I doing in this handbasket?"

Wes Peters                                                 Softweyr LLC
http://www.softweyr.com/~softweyr                      wes@softweyr.com


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