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

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

About import/export.

The problem with HW is that it always handles 64 byte blocks except last 
one.
So until finup/final it is not known if it is the last data. So some 
buffer is kept in context.

With DMA it is very inefficient to have small buffer.
I use page 4k for that.
So after a certain update there is a data in the cache.

Doing export means that we need to get out intermediate hash and that 
buffer.

Any suggestion?

Thanks


On 13/04/10 17:48, ext Herbert Xu wrote:
> On Tue, Apr 13, 2010 at 04:44:35PM +0300, Dmitry Kasatkin wrote:
>    
>> Well it can... if reqa occupied hw all other requests will fallback to
>> sw sha1.
>>      
> That is unacceptable.  If we had a user-space API that would
> mean a single request can tie up the hardware indefinitely.
>
> If your hardware is not able to produce a non-finalised hash,
> then you should only do finup/final in hardware, and use a software
> fallback to implement the rest.
>
>    
> If your hardware is also not able to accept an initial state,
> then the only thing you can implement is digest.  The rest would
> have to fall back to software.
>
> Cheers,
>