Re: [PATCH v2 09/10] crypto: caam - add crypto_engine support for RSA algorithms

[Iuliana Prodan]

On 1/14/2020 2:14 AM, Herbert Xu wrote:
> On Mon, Jan 13, 2020 at 09:48:11AM +0000, Iuliana Prodan wrote:
>>
>> Regarding the transfer request to crypto-engine: if sending all requests
>> to crypto-engine, multibuffer tests, for non-backlogging requests fail
>> after only 10 requests, since crypto-engine queue has 10 entries.
> 
> That isn't right.  The crypto engine should never refuse to accept
> a request 
Crypto-engine accepts all request that have the backlog flag, the 
non-backlog are accepted till the configured limit (of 10).

> unless the hardware queue is really full.  
Crypto-engine doesn't check the status of hardware queue.
The non-backlog requests are dropped after 10 entries.

> Perhaps the
> crypto engine code needs to be fixed?
To me, crypto-engine seems to be made for backlogged request, that's why 
I'm sending the non-backlog directly to CAAM. The implicit serialization 
of request in crypto-engine is the bottleneck.

But, as I said before, I want to update crypto-engine to set queue 
length when initialize crypto-engine, and remove serialization of 
requests in crypto-engine by adding knowledge about the underlying hw 
accelerator (number of request that can be processed in parallel).
I'll send a RFC with my proposal for crypto-engine enhancements.

But, until then, I would like to have a backlogging solution in CAAM driver.

Thanks,
Iulia