0 5:09 AM
>> To: Subrahmanya, Chaithrika
>> Cc: davinci-linux-open-source@linux.davincidsp.com
>> Subject: Re: Audio quality with CPU frequency scaling
>>
>> "Chaithrika U S" writes:
>>
>> > Kevin,
>> >
>> > With the cpufreq su
nci-linux-open-source@linux.davincidsp.com
> Subject: Re: Audio quality with CPU frequency scaling
>
> "Chaithrika U S" writes:
>
> > Kevin,
> >
> > With the cpufreq support on DA850/OMAP-L138 SoC we are observing
> > that audio does not function as expect
Something doesn't make sense. Say we take a case stated not to work, ie
16 kHz with CPU at 96 MHz. If
we assume stereo input and output running at simultaneously we have
16000 samples/sec x 4 audio channel x 1 EDMA transfer/audio channel =
64,000 EDMA transfer/second
Give a clock rate of 96 M
"Chaithrika U S" writes:
> Kevin,
>
> With the cpufreq support on DA850/OMAP-L138 SoC we are observing
> that audio does not function as expected at all sampling rates
> for various operating points. At a CPU frequency of 96MHz, audio
> works fine with a sampling frequency of 8kHz. For other samp
Andrew,
Thank you for your inputs.
> Can you elaborate on your "EDMA runs at a lower speed" comment ? The
> usual setup is to have McASP trigger EDMA transfer. An EDMA transfer
> runs at CPU speed. It should be plenty fast enough at 96 MHz.
>
EDMA here runs at 48MHz and McASP triggers the EDM
Chaithrika,
Can you elaborate on your "EDMA runs at a lower speed" comment ? The
usual setup is to have McASP trigger EDMA transfer. An EDMA transfer
runs at CPU speed. It should be plenty fast enough at 96 MHz.
In the past I have seen issues where the CPU cache updating has priority
over th
Kevin,
With the cpufreq support on DA850/OMAP-L138 SoC we are observing
that audio does not function as expected at all sampling rates
for various operating points. At a CPU frequency of 96MHz, audio
works fine with a sampling frequency of 8kHz. For other sampling
rates, there are lot of underrun/
