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

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

On 14/04/10 09:44, ext Herbert Xu wrote:
> On Wed, Apr 14, 2010 at 09:37:47AM +0300, Dmitry Kasatkin wrote:
>    
>> Like just with import/export.
>> Problems for hw:
>>
>> 1. To have a good performance with DMA we need to have large buffer.
>>      Not just 64 bytes block. state becomes large
>>      
> Sure.  But it shouldn't be up to the driver to merge operations.
> Higher layers (either the end-user or the crypto API) should perform
> merging.
>
>    
What do you mean by "merge operation".
request merging?

> We don't put request merging into storage drivers for a reason.
>
>    
>> 2. supporting concurrent requests means switching HW state and it takes
>> a time.
>>      
> Well that's just the way it is.  I'm not saying that it's going
> to occur frequently, but if it does, you need to support it.
>
>    
>> All that burden significantly slowdown hw acceleration and increase CPU
>> load.
>>
>> I guess my points are understandable.
>>      
> I understand your concerns, but these are really limitations
> common to all off-chip acceleration.  If you have to write drivers
> for them, then you'll have to deal with these issues.
>
> Cheers,
>