[PATCH v2 2/2] Crypto: Talitos: Support for Async_tx XOR offload

Kumar Gala galak at kernel.crashing.org
Fri Dec 18 04:29:26 EST 2009

On Dec 17, 2009, at 11:09 AM, Ira W. Snyder wrote:

> On Wed, Dec 16, 2009 at 03:47:48PM -0700, Dan Williams wrote:
>> Kumar Gala wrote:
>>>>> Changes with respect to v1 as per comments received
>>>>> o. Rebased to linux-next as of 20091216
>>>>> o. The selection is based exclusive of fsldma
>>>>> o. Intoduced a new Kernel Configuration variable
>>>>>  *. This enables selecting the Cryptographic functionality
>>>>>     of Talitos along with fsldma.
>>>>>  *. Disables the XOR parity calculation offload, if fsldma enabled
>>>>>     either as kernel in-built or as a module
>>>>>  *. Once the inter-operability with fsldma is resolved, this option
>>>>>     can be removed
>>>> wait, why can't the interoperability bug be fixed in the first place?
>>> I agree w/Kim.  We need to better understand what the bug is and how to reproduce it so we can get to the root cause.
>>> Paper taping over it by disabling fsldma is not the right solution.
>> Hopefully this prompts fsldma authors to get involved because the 
>> interoperability issue has been out there without comment*, just 
>> band-aids, since October.
>> --
>> Dan
>> * well one comment from Ira saying the interrupt functionality worked 
>> for him.
> Yes, I have used the device_prep_dma_interrupt() functionality quite a
> while back. However, I found it to be pretty much useless. Any
> functionality I need is covered by adding a callback to the last DMA
> memcpy() operation. Since the operations happen in-order, I can be sure
> that the entire set of memcpy()s cas completed. I never needed the
> capability to generate an interrupt without a memcpy().
> I agree that the fsldma driver could use some love. There are places
> where I am still not confident in the locking. Perhaps I can find some
> time over Christmas to work on it, but I need someone with 85xx/86xx
> hardware to test the changes. I only have 83xx hardware.

I can test on 85xx/86xx if you work up some patches.

- k

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