linux-kernel - Re: Kernel Summit request for Discussion of future of ATA (libata) and IDE

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Message-ID: <4898F3EA.7000507@gmail.com>
Date:	Wed, 06 Aug 2008 09:44:26 +0900
From:	Tejun Heo <htejun@...il.com>
To:	Robert Hancock <hancockr@...w.ca>
CC:	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>,
	James Bottomley <James.Bottomley@...senpartnership.com>,
	ksummit-2008-discuss@...ts.linux-foundation.org,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-ide <linux-ide@...r.kernel.org>,
	Jeff Garzik <jeff@...zik.org>
Subject: Re: Kernel Summit request for Discussion of future of ATA (libata)
 and IDE

Robert Hancock wrote:
> Here's my first cut at it. Compile tested only. This sets most controllers
> to use 32-bit PIO except for those which could potentially be on a real ISA
> or other 16-bit bus. It's a bit non-obvious what to do with some of the
> drivers, so input is welcome.
> 
> This implementation doesn't check the ata_id_has_dword_io at all, since it
> would only make a difference on controllers where we don't really want to
> use it anyway.
> 
> It seems like regardless of whether we do 32-bit by default or not the 32-bit
> data_xfer function should be added to libata core as we have several drivers
> which duplicate the same code currently..

Great, just some minor nitpicks as I don't have much idea about 16 bit ones.

> +unsigned int ata_sff_data_xfer(struct ata_device *dev, unsigned char *buf,
> +			       unsigned int buflen, int rw)
> +{
> +	struct ata_port *ap = dev->link->ap;
> +	void __iomem *data_addr = ap->ioaddr.data_addr;
> +	unsigned int words = buflen >> 2;

dwords maybe?

> +	unsigned int slop = buflen & 3;
> +
> +	/* Transfer multiple of 4 bytes */
> +	if (rw == READ)
> +		ioread32_rep(data_addr, buf, words);
> +	else
> +		iowrite32_rep(data_addr, buf, words);
> +
> +	/* Transfer trailing 1 byte, if any. */

1byte?

Thanks.

-- 
tejun
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