Re: How to add full duplex capture and playback?

[Hans-Christian Egtvedt <hcegtvedt@atmel.com>]

Takashi Iwai wrote:
> At Fri, 19 May 2006 17:42:55 +0200,
> Hans-Christian Egtvedt wrote:
>> Takashi Iwai wrote:
>>> At Fri, 19 May 2006 12:44:58 +0200,
>>> Hans-Christian Egtvedt wrote:

<snipp code>

>> But it does not work quite as expected. I'm still able to set rate and
>> format from userspace (aplay/arecord), and this again will alter the
>> hardware setup when the prepare callback is called.
> 
> Right.  The restriction of configuration space is defined by the rules
> set in open callback.  hw_params callback just follows the given
> parameter and returns the success or the failure code.
> 
> A typical code is like below:

<snipp code example>

Thank you, this really clear things up. Driver is working as expected now.

> In addition, a proper mutex would be preferred around the operation.
> 
> To be more strict, we may change hw_params like the following:

<snipp code example>

> However, this doesn't work with OSS emulation because OSS emulation
> initializes the rate to a certain default one.  If app tries to change
> the rate in the full-duplex mode, then it's refused.

I will leave this part out for now, since it dosn't work with OSS
emaulation.

-- 
With kind regards,
Med vennlig hilsen,

Hans-Christian Egtvedt
Applications Engineer - AVR Applications Lab
Atmel Norway


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