Re: [RFC PATCH v2 1/9] crypto: qce: Add core driver implementation

[Stanimir Varbanov]

Hi Herbert,

On 04/28/2014 11:59 AM, Herbert Xu wrote:
> On Mon, Apr 14, 2014 at 03:48:37PM +0300, Stanimir Varbanov wrote:
>>
>> +#define QCE_MAJOR_VERSION5	0x05
>> +#define QCE_QUEUE_LENGTH	50
> 
> What is the purpose of this software queue? Why can't you directly
> feed the requests to the hardware?

Good question. This is a leftover from original driver.

The hardware can handle one request at a time. After you raise the
question I think the queue length should be 1 or remove it completely. I
don't know why the original codeaurora's driver use 50.

> 
> If the hardware can't handle more than 50 requests in-flight,
> then your software queue has failed to handle this since you're
> taking requests off the queue before you touch the hardware so
> you're not really limiting it to 50.  That is, for users that
> can wait you're potentially dropping their requests instead
> of letting them wait through the backlog mechanism.

-- 
regards,
Stan
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