linux-kernel - Re: [PATCH] sata_sil: add Large Block Transfer support

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Message-ID: <494F69C4.2060708@kernel.org>
Date:	Mon, 22 Dec 2008 19:19:48 +0900
From:	Tejun Heo <tj@...nel.org>
To:	Robert Hancock <hancockr@...w.ca>
CC:	ide <linux-ide@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] sata_sil: add Large Block Transfer support

Hello,

Robert Hancock wrote:
> Obviously not 2.6.28 material, but could potentially head into .29.
> I've done some testing with a DVD drive connected to this controller
> and verified that reading off an entire DVD returns correct data
> (and that the controller is actually getting requests that cross
> 64K boundaries). More testing would certainly be useful..

Ah... nice.  It would be great to have this in -next for some time.

> +static void sil_bmdma_stop(struct ata_queued_cmd *qc)
> +{
> +    struct ata_port *ap = qc->ap;
> +    void __iomem *mmio_base = ap->host->iomap[SIL_MMIO_BAR];
> +    void __iomem *bmdma2 = mmio_base + sil_port[ap->port_no].bmdma2;
> +
> +    /* clear start/stop bit - can safely always write 0 */
> +    writeb(0, bmdma2);

ioread/iowrite?

> +    /* one-PIO-cycle guaranteed wait, per spec, for HDMA1:0 transition */
> +    ata_sff_dma_pause(ap);
> +}
> +
> +static void sil_bmdma_setup(struct ata_queued_cmd *qc)
> +{
> +    struct ata_port *ap = qc->ap;
> +    void __iomem *bmdma = ap->ioaddr.bmdma_addr;
> +
> +    /* load PRD table addr. */
> +    mb();    /* make sure PRD table writes are visible to controller */

I know it's not specific to this change but does mb() really make
sense here?  I don't think we need any barrier here.

> +    writel(ap->prd_dma, bmdma + ATA_DMA_TABLE_OFS);
> +
> +    /* issue r/w command */
> +    ap->ops->sff_exec_command(ap, &qc->tf);
> +}

Thanks.

-- 
tejun
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