Date: Sun, 5 Feb 2006 22:43:12 -0500
From: William Park <opengeometry@yahoo.ca>
To: linux-kernel@vger.kernel.org
Subject: DMA in PCI chipset -- module vs. compiled-in
Message-ID: <20060206034312.GA2962@node1.opengeometry.net>
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Dear experts,

Normally, my PCI chipset (ie. via82cxxx, hpt366) are compiled in, and it
correctly enables DMA of my harddisk.

But, for experiment, I tried compiling in only the "generic" options,
and moved all specific PCI chipsets as modules.  Hotplug loads the
modules, but with all 'hdparm' options turned off.  When I tried turning
on DMA, 
    $ hdparm -m 16 -c 1 -u 1 -d 1 /dev/hda
I get
    /dev/hda:
     setting 32-bit IO_support flag to 1
     setting multcount to 16
     setting unmaskirq to 1 (on)
     setting using_dma to 1 (on)
     HDIO_SET_DMA failed: Operation not permitted
     multcount    = 16 (on)
     IO_support   =  1 (32-bit)
     unmaskirq    =  1 (on)
     using_dma    =  0 (off)

Is this normal?  How do I turn on DMA, if I load my PCI chipset as
module?

-- 
William Park <opengeometry@yahoo.ca>, Toronto, Canada
ThinFlash: Linux thin-client on USB key (flash) drive
	   http://home.eol.ca/~parkw/thinflash.html
BashDiff: Super Bash shell
	  http://freshmeat.net/projects/bashdiff/
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