From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Subject: Re: [PATCH 2/6] pata_sis: Implement MWDMA for the UDMA 133 capable
 chips
Date: Mon, 07 Dec 2009 16:26:00 +0300
Message-ID: <4B1D0268.4090508@ru.mvista.com>
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To: Alan Cox <alan@linux.intel.com>
Cc: linux-ide@vger.kernel.org, jeff@garzik.org, davem@davemloft.net

Hello.

Alan Cox wrote:

> Bartlomiej pointed out that while this got fixed in the old driver whoever
> did it didn't port it across.

> Signed-off-by: Alan Cox <alan@linux.intel.com>

[...]

> +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);
> +}

    You call min() on uncomparables, i.e. mwdma_to_pio[] contains XFER_PIO_* 
and adev->pio_mode - XFER_PIO_0 yields you a mode number. Thus the second 
argument will always "win" as a minimal one.

MBR, Sergei