Messages in this thread | | | Date | Sun, 06 Jan 2008 17:13:35 +0100 | From | Zoltan Boszormenyi <> | Subject | [PATCH] Re: Forcing modes in libata (was: SATA buffered read VERY |
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Hi,
Once upon a time FD Cami wrote: > On Sun, 6 Jan 2008 13:36:09 +0000 > Alan Cox <alan@lxorguk.ukuu.org.uk> wrote: > > > On Sun, 6 Jan 2008 08:03:31 +0300 > > > > For now you can boot with libata.dma=1 to select DMA on disks but > > > > not CD > > > > > > Great, but why isn't this in the documentation? > > > > Send patches > > patch attached. > > Description : Add libata.dma= to Documentation/kernel-parameters.txt > > Found documentation in : > http://www.mail-archive.com/linux-ide%40vger.kernel.org/msg09849.html > http://www.redhat.com/archives/fedora-extras-commits/2007-October/msg04568.html > > Signed-off-by: François Cami <francois.cami@free.fr> > > *["libata-doc-patch.txt" (text/plain)]* <http://marc.info/?l=linux-kernel&m=119963307018562&q=p3> > > diff -rU2 linux-2.6.24-rc6/Documentation/kernel-parameters.txt \ > linux-2.6.24-rc6-mine/Documentation/kernel-parameters.txt > --- linux-2.6.24-rc6/Documentation/kernel-parameters.txt 2008-01-06 \ > 15:58:54.000000000 +0100 > +++ linux-2.6.24-rc6-mine/Documentation/kernel-parameters.txt 2008-01-06 \ > 16:11:20.000000000 +0100 @@ -883,4 +883,11 @@ > C2 power state. > > + libata.dma= [LIBATA] DMA control > + libata.dma=0 Disable all PATA DMA like old IDE > + libata.dma=1 Disk DMA only > + libata.dma=2 ATAPI DMA only > + libata.dma=3 CF DMA only > + libata.dma=0,1,3 Combinations also work. > + >
The code patch you are looking at has little different semantics. (1 << 2) is 4 not 3... Values for different devices are:
1 - ATA 2 - ATAPI 4 - CF
The parameter is a bitmask of 1, 2, 4. Default is 7. 2.6.24-rc3 also has this in libata-core.c which confirms the acceptance of a bitmask :
static int libata_dma_mask = ATA_DMA_MASK_ATA|ATA_DMA_MASK_ATAPI|ATA_DMA_MASK_CFA; module_param_named(dma, libata_dma_mask, int, 0444); MODULE_PARM_DESC(dma, "DMA enable/disable (0x1==ATA, 0x2==ATAPI, 0x4==CF)");
Best regards, Zoltán Böszörményi
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