Date: Wed, 17 Sep 2003 03:42:37 -0700
From: Reza Naima <reza@reza.net>
To: Kernel List <linux-kernel@vger.kernel.org>
Subject: i810_audio bug (?)
Message-ID: <20030917104237.GB21397@boom.net>
Reply-To: Reza Naima <reza@reza.net>
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When I pass audio_samplerate = 32000 to 

       ioctl(afd, SNDCTL_DSP_SPEED, &audio_samplerate)

it changes my audio_sample rate from 32000 to 31627.

Now, this is causing problems with my downstream apps so I did some
investigating. Looking into i810_set_adc_rate() in i810_audio.c, 
there is some wierd math going on..

1) first, the original rate (32000) is converted to a new rate ..

	rate = (rate * clocking)/48000

	where clocking, in my case, is 48566. 

2) this new value is fed into newrate=ac97_set_adc_rate() which returns 
   the orignal sampling rate value (32000).  This number is then modified
   by the ratio

	dmabuf->rate = newrate * 48000 / clocking.

3) This results in the value 31627 that I'm seeing.  Now, is this the
   actual sample rate, or some internal value used to generate a 32000kbps
   sample rate?  If so, is it perhaps a bug that dmabuf->rate is being
   returned rather than newrate?


Thanks,
-Reza


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