Re: [PATCH] ahci: disable FPDMA auto-activate optimization on NVIDIA AHCI

[Prajakta Gudadhe <pgudadhe@nvidia.com>]

We are currently investigating this MCP79 issue when FPDMA auto activate
feature is enabled. Meanwhile, this patch looks good to me.

--Prajakta Gudadhe

On Tue, 2010-01-26 at 20:33 -0800, Robert Hancock wrote:
> Mike Cui reported that his system with an NVIDIA MCP79 (aka MCP7A) chipset
> stopped working with 2.6.32. The problem appears to be that 2.6.32 now enables
> the FPDMA auto-activate optimization in the ahci driver. The drive works fine
> with this enabled on an Intel AHCI so this appears to be a chipset bug.
> Since MCP79 is a fairly recent NVIDIA chipset and we don't have any info on
> whether any other NVIDIA chipsets have this issue, disable FPDMA AA optimization
> on all NVIDIA AHCI controllers for now.
> 
> Should address http://bugzilla.kernel.org/show_bug.cgi?id=14922
> 
> Signed-off-by: Robert Hancock <hancockrwd@gmail.com>
> 
> ---
> 
> Mike, can you test this out and make sure this resolves the problem for you?
> 
> diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
> index b8bea10..47e57dc 100644
> --- a/drivers/ata/ahci.c
> +++ b/drivers/ata/ahci.c
> @@ -3067,8 +3067,16 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
>  	ahci_save_initial_config(pdev, hpriv);
>  
>  	/* prepare host */
> -	if (hpriv->cap & HOST_CAP_NCQ)
> -		pi.flags |= ATA_FLAG_NCQ | ATA_FLAG_FPDMA_AA;
> +	if (hpriv->cap & HOST_CAP_NCQ) {
> +		pi.flags |= ATA_FLAG_NCQ;
> +		/* Auto-activate optimization is supposed to be supported on
> +		   all AHCI controllers indicating NCQ support, but it seems
> +		   to be broken at least on some NVIDIA MCP79 chipsets.
> +		   Until we get info on which NVIDIA chipsets don't have this
> +		   issue, if any, disable AA on all NVIDIA AHCIs. */
> +		if (pdev->vendor != PCI_VENDOR_ID_NVIDIA)
> +			pi.flags |= ATA_FLAG_FPDMA_AA;
> +	}
>  
>  	if (hpriv->cap & HOST_CAP_PMP)
>  		pi.flags |= ATA_FLAG_PMP;
> --
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