On Sun, 6 Jan 2008 17:27:38 +0100
Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> wrote:

quoted text
> On Sunday 06 January 2008, FD Cami wrote:
> > On Sun, 6 Jan 2008 13:36:09 +0000
> > Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> >=20
> > > On Sun, 6 Jan 2008 08:03:31 +0300
> > > > > For now you can boot with libata.dma=3D1 to select DMA on disks
> > > > > but not CD
> > > >=20
> > > > Great, but why isn't this in the documentation?
> > >=20
> > > Send patches
> >=20
> > patch attached.
> >=20
> > Description : Add libata.dma=3D to Documentation/kernel-parameters.txt
> >=20
> > 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/msg04=
568.html
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> >=20
> > Signed-off-by: Fran=C3=A7ois Cami <francois.cami@free.fr>
>=20
> diff -rU2 linux-2.6.24-rc6/Documentation/kernel-parameters.txt=20
> linux-2.6.24-rc6-mine/Documentation/kernel-parameters.txt
> ---
> linux-2.6.24-rc6/Documentation/kernel-parameters.txt=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A02008-01-06
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> 15:58:54.000000000 +0100 +++
> linux-2.6.24-rc6-mine/Documentation/kernel-parameters.txt=C2=A0=C2=A0=C2=
=A02008-01-06
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> 16:11:20.000000000 +0100 @@ -883,4 +883,11 @@ C2 power state.=20
> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0libata.dma=3D=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0[LIBATA] DMA control
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> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0libata.dm=
a=3D0=C2=A0=C2=A0=C2=A0=C2=A0 =C2=A0Disable all PATA DMA like
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> old IDE
>=20
> this doesn't seem entirely correct:
>=20
> * IDE has "hdx=3Dnodma" so you can disable DMA on per-device basis

I think that libata.dma=3D1 is designed to behave like=20
CONFIG_IDEDMA_ONLYDISK used to. "hdx=3Dnodma" is more fine-grained than
this.

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> * is this really limited to PATA?

Alan's original patch took care of PATA. SATA support was added
later by Jeff Garzik. Corrected documentation patch attached.

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> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0libata.dm=
a=3D1=C2=A0=C2=A0=C2=A0=C2=A0 =C2=A0Disk DMA only
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> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0libata.dm=
a=3D2=C2=A0=C2=A0=C2=A0=C2=A0 =C2=A0ATAPI DMA only
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> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0libata.dm=
a=3D3=C2=A0=C2=A0=C2=A0=C2=A0 =C2=A0CF DMA only=20

This is also wrong, it should be "libata.dma=3D4=C2=A0=C2=A0=C2=A0=C2=A0 =
=C2=A0CF DMA only"
Thanks to Zoltan Boszormenyi <zboszor@dunaweb.hu> for catching this
mistake.

Revised patch attached.

Best,

Fran=C3=A7ois