109 lines
3.3 KiB
Groff
109 lines
3.3 KiB
Groff
.\" $NetBSD: geodeide.4,v 1.4 2005/07/06 06:36:10 fair Exp $
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.\"
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.\" Copyright (c) 2004 Manuel Bouyer.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by Manuel Bouyer.
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.\" 4. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd July 5, 2005
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.Dt GEODEIDE 4
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.Os
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.Sh NAME
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.Nm geodeide
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.Nd AMD Geode IDE disk controllers driver
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.Sh SYNOPSIS
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.Cd "geodeide* at pci? dev ? function ? flags 0x0000"
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.Sh DESCRIPTION
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The
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.Nm
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driver supports the
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.Tn AMD
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Geode CS5530A and SC1100
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.Tn IDE
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controllers,
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and provides the interface with the hardware for the
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.Xr ata 4
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driver.
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.Pp
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The 0x0002 flag forces the
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.Nm
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driver to disable
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.Tn DMA
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on chipsets for which
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.Tn DMA
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would normally be enabled.
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This can be used as a debugging aid, or to work around
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problems where the
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.Tn IDE
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controller is wired up to the system incorrectly.
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.Sh SEE ALSO
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.Xr ata 4 ,
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.Xr atapi 4 ,
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.Xr intro 4 ,
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.Xr pci 4 ,
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.Xr pciide 4 ,
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.Xr wd 4 ,
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.Xr wdc 4
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.Sh BUGS
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The SC1100 controller requires 4-byte aligned data transfers and
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cannot handle transfers of exactly 64 kilobytes.
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.Pp
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The CS5530 multifunction chip/core's
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.Tn IDE
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section claims to be capable of
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.Tn UDMA
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mode 2
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.Pq 33.3MB/s
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but in practice using that mode swamps the controller so badly that
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.Nm
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limits the
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.Tn UDMA
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negotiation to mode 1
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.Pq 25MB/s
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so that the other functions of this chip continue to work.
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.Pp
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The
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.Tn IDE DMA
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engine in the CS5530 can only do transfers on cache-line
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.Pq 16-byte
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boundaries.
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Attempts to perform
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.Tn DMA
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on any other alignment will crash the system.
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This problem may also exist in the SC1100 since the CS5530 was its
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direct predecessor, and it is not clear that National Semiconductor
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fixed any bugs in it.
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.Pp
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The
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.Nm
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driver will reject attempts to
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.Tn DMA
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to buffers not aligned to the required boundary.
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The
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.Xr wd 4
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disk driver will back off to
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.Tn PIO
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mode to accomplish these transfer requests, at reduced system performance.
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