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From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: [PATCH 2/5] pata_sis: Implement MWDMA for the UDMA 133 capable chips
Date: Tue, 17 Nov 2009 18:57:01 +0100
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Cc: Alan Cox <alan@linux.intel.com>, linux-kernel@vger.kernel.org,
       linux-ide@vger.kernel.org
References: <20091117144450.15430.83450.stgit@localhost.localdomain> <200911171827.29891.bzolnier@gmail.com> <20091117173823.217b95a7@lxorguk.ukuu.org.uk>
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On Tuesday 17 November 2009 18:38:23 Alan Cox wrote:
> > > +static int mwdma_clip_to_pio(struct ata_device *adev)
> > > +{
> > > +	const int mwdma_to_pio[3] = {
> > > +		XFER_PIO_0, XFER_PIO_3, XFER_PIO_4
> > > +	};
> > > +	return min(mwdma_to_pio[adev->dma_mode - XFER_MW_DMA_0],
> > > +				adev->pio_mode - XFER_PIO_0);
> > > +}
> > 
> > This wants to be in the generic libata code.
> 
> I'm not convinced because for the majority of drivers the libata timing
> interface handles it. SiS needs it just because it does things by
> precomputed tables. It's a one off interface.

Controllers based on *Intel* PIIX are in the disagreement with the above
paragraph and having generic helper to do conversion (without a clipping)
would bring us a little step closer to killing a needless code duplication
currently present in their ->set_piomode and ->set_dmamode methods.

[ In case somebody wonders: no, 'old' drivers don't have such duplication
  and 'whoever did it didn't port it across' cause said 'whoever'-s were not
  into the development of the square wheels.... ]

-- 
Bartlomiej Zolnierkiewicz
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