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

[Robert Hancock <hancockrwd@gmail.com>]

Jeff, ping? Without further input from NVIDIA, I think we may want to
get this in for 2.6.33.

On Tue, Feb 16, 2010 at 4:46 PM, Prajakta Gudadhe <pgudadhe@nvidia.com> wrote:
> 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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>
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