Re: [PATCH] libata: implement and use DMA mask configuration helper

[Jeff Garzik <jeff@garzik.org>]

Tejun Heo wrote:
> Jeff Garzik wrote:
>> Tejun Heo wrote:
>>> Implement and use DMA mask configuration helper.
>>>
>>> Signed-off-by: Tejun Heo <htejun@gmail.com>
>>> ---
>>> This function probably belongs to pci layer.  Put it in libata with
>>> pci_test_bits() for the time being.
>> AFAIK the default DMA mask is always 32-bit.  Code (often written by me)
>> that sets it to a 32-bit mask was just paranoia, and not really needed.
>>
>> Hence, the pci_go_64() function I added, found in #upstream.
> 
> It isn't in #upstream yet.  Also, at the second thought, there is a
> problem with pci_go_64().  DMA masks are not reset after driver is
> detached.  Even if the device starts with 32bit DMA masks, after a 64bit
> enabled driver is attached and detached, the device's DMA masks are
> 64bit.  I'm refreshing new-init-model patchset and keeping
> pci_configure_dma_masks() for now.

That "problem" has existed since day one, and nobody seems to care :)

I can't think of a single 64-bit-capable driver that restores the masks, 
and can't think of a single bug report that resulted from it.

	Jeff