Re: [PATCH 0/2] crypto: omap-sha1-md5: OMAP3 SHA1 & MD5 driver

[Dmitry Kasatkin <dmitry.kasatkin@nokia.com>]

Please see inline. Nice to clarify it.

On 13/04/10 15:10, ext Herbert Xu wrote:
> On Tue, Apr 13, 2010 at 01:15:34PM +0300, Dmitry Kasatkin wrote:
>    
>> But anyway hmac does not support ahash now. right?
>> So the only way currently is to add to the driver.
>>      
> No the only way is to add an ahash version of hmac.
>
> Anyway, the fact that you can't easily implement import/export
> is not just a question of supporting hmac.  It is in fact a sign
> that your driver breaks the crypto API.
>
> The fundamental requirement for the ahash interface is that you
> must be able to launch multiple operations, which means that all
> state must be stored in the request and not held in hardware
> (except as a cache).
>
> IOW, you must be able to support
>
> 	crypto_ahash_update(&reqa);
>
> 	...
>
> 	crypto_ahash_update(&reqb);
>
> 	...
>
> 	ahash_request_set_crypt(&reqa, ...);
> 	crypto_ahash_finup(&reqa);
>
> 	...
>
> 	ahash_request_set_crypt(&reqb, ...);
> 	crypto_ahash_finup(&reqb);
>
> AFAICS your driver cannot do this correctly in its current form.
>
>    
Well it can... if reqa occupied hw all other requests will fallback to 
sw sha1.

But if to do only hw and to follow above algorithm then it is necessary 
to remove shash support completely from the driver.
And have a queue as I have with aes driver..
err = ablkcipher_enqueue_request(&dd->queue, req);

I see there is ahash_enqueue_request() which is in 
crypto/internal/hash.h and NEVER called.

Also in one of your earlier emails you said that it is not possible to 
call crypto_ahash_update() before completion.
But with having a queue it does not really matter.
Possible to queue several update request from the same tfm.

The only need to wait_for_completion is to export/get results...

Can you confirm my understanding?

Thanks



Well. not like that.

> Thanks,
>