From: Andrew Morton <akpm@zip.com.au>
To: Ed Sweetman <ed.sweetman@wmich.edu>
Cc: Kristian <kristian.peters@korseby.net>, linux-kernel@vger.kernel.org
Subject: Re: [CFT] Bus mastering support for IDE CDROM audio
Date: Mon, 28 Jan 2002 00:29:08 -0800 [thread overview]
Message-ID: <3C550BD4.E9CBE6A@zip.com.au> (raw)
In-Reply-To: <20020127111917.3c019701.kristian.peters@korseby.net>, <3C5119E0.6E5C45B6@zip.com.au> <000701c1a5d5$812ef580$6caaa8c0@kevin> <3C53711B.F8D89811@zip.com.au> <3C53A116.81432588@zip.com.au> <20020127101131.0f71e978.kristian.peters@korseby.net> <20020127111917.3c019701.kristian.peters@korseby.net> <1012161271.22707.50.camel@psuedomode>
OK, Gents. Version three is at
http://www.zip.com.au/~akpm/linux/2.4/2.4.18-pre7/ide-akpm-3.patch
This attempts to overcome the situation where a drive/controller
doesn't want to perform multiframe DMA, but is happy performing
single-frame DMA.
So:
- We start out trying to perform multiframe DMA. If we get
a DMA error, we fall back to single-frame DMA.
- If we get a DMA error in single frame mode, we fall back
to multi-frame PIO.
At no stage does a packet-mode DMA error turn off drive-level
DMA. This is because some devices seem to perform ordinary
ATA DMA OK, but screw up packet DMA.
The kernel internally retries the requests when it performs fallback,
so userspace shouldn't see any disruption as the kernel works
out what to do.
Once the drive has fallen back to single-frame (or PIO mode) for
packet reads, the only way to get it back to a higher level is
a reboot.
-
next prev parent reply other threads:[~2002-01-28 8:37 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-01-25 8:40 [CFT] Bus mastering support for IDE CDROM audio Andrew Morton
2002-01-25 19:21 ` Kevin P. Fleming
2002-01-27 2:13 ` Dan Chen
2002-01-27 3:16 ` Andrew Morton
2002-01-27 6:41 ` Andrew Morton
2002-01-27 9:11 ` Kristian
2002-01-27 10:19 ` Kristian
2002-01-27 19:54 ` Ed Sweetman
2002-01-28 8:29 ` Andrew Morton [this message]
2002-01-28 9:51 ` benh
2002-01-28 9:51 ` Andrew Morton
2002-01-28 15:50 ` Ed Sweetman
2002-01-28 17:13 ` Kristian
2002-01-28 13:51 ` Kristian
2002-01-28 19:21 ` Kevin P. Fleming
2002-01-26 8:43 ` Dan Chen
2002-01-26 12:03 ` Kristian
2002-01-27 21:21 ` Robert Love
2002-01-27 21:25 ` Jens Axboe
2002-01-27 21:36 ` Andrew Morton
2002-01-27 21:40 ` Robert Love
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