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Date: Sat, 14 Oct 2000 18:20:27 -0400 (EDT)
From: Thomas Valentino Crimi <tcrimi+@andrew.cmu.edu>
To: "Andrew M. Miklic" <miklic@attglobal.net>
Subject: Re: TGA and PCI
Cc: freebsd-alpha@freebsd.org
In-Reply-To: <39E87745.596865AC@attglobal.net>
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  I tried to write a TGA driver as well although but never finished it. 
At the point I left it the driver registered itself with syscons and
drew a pattern on the screen.  I'd be more than happy to send you the
source if it can help any.

  From reading the code the driver is both registed as a PCI device and
as a VIDEO_DRIVER, the PCI probe and attach functions are called first. 
In tga_pci_probe I use pci_get_vendor/device on the device_t structure
passed.

tga_pci_attach maps the video car into memory using:

        res = bus_alloc_resource(dev, SYS_RES_MEMORY, &reg,
                                 0, ~0, 1, RF_ACTIVE | PCI_RF_DENSE);
where reg = PCIR_MAPS

 and puts necessary information in tga_adapter[i], an array of
video_adapter_t, and calls vidregister() on it.  So, before anything
happens with sccnattach all pci configuration data has been read.  If
the card didn't sucessfully probe and attach the vi_probe_t or backdoor
function would never find it.

  syscons eventually calls the backdoor fucnction which checks that
something has been set in tga_adapters[] and calls the card
initialization function on it, which find out which version of TGA card
is present, sets up the resolution and draws the pattern.


 Best of luck finishing up the driver
-- Tom 


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