Re: [PATCH] Re: Forcing modes in libata (was: SATA buffered read VERY slow)

[Bartlomiej Zolnierkiewicz]

On Sunday 06 January 2008, FD Cami wrote:
> On Sun, 6 Jan 2008 17:27:38 +0100
> Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx> wrote:
> 
> > On Sunday 06 January 2008, FD Cami wrote:
> > > On Sun, 6 Jan 2008 13:36:09 +0000
> > > Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> 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: FranÃois Cami <francois.cami@xxxxxxx>
> > 
> > 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.txtÂÂÂÂÂÂÂÂ2008-01-06
> > 15:58:54.000000000 +0100 +++
> > linux-2.6.24-rc6-mine/Documentation/kernel-parameters.txtÂÂÂ2008-01-06
> > 16:11:20.000000000 +0100 @@ -883,4 +883,11 @@ C2 power state. 
> > +ÂÂÂÂÂÂÂlibata.dma=ÂÂÂÂÂ[LIBATA] DMA control
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂlibata.dma=0ÂÂÂÂ ÂDisable all PATA DMA like
> > old IDE
> > 
> > this doesn't seem entirely correct:
> > 
> > * IDE has "hdx=nodma" so you can disable DMA on per-device basis
> 
> I think that libata.dma=1 is designed to behave like 
> CONFIG_IDEDMA_ONLYDISK used to. "hdx=nodma" is more fine-grained than
> this.

Seems so but CONFIG_IDEDMA_ONLYDISK was removed on the same day
that "hdx=nodma" was introduced (Oct 16 2007)...

> > * 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.
> 
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂlibata.dma=1ÂÂÂÂ ÂDisk DMA only
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂlibata.dma=2ÂÂÂÂ ÂATAPI DMA only
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂlibata.dma=3ÂÂÂÂ ÂCF DMA only 
> 
> This is also wrong, it should be "libata.dma=4ÂÂÂÂ ÂCF DMA only"
> Thanks to Zoltan Boszormenyi <zboszor@xxxxxxxxxx> for catching this
> mistake.
> 
> Revised patch attached.

Thanks, looks good to me.

Bart
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