On Fri, May 20, 2016 at 11:12:39AM +0800, John Hsu wrote: > On 5/19/2016 1:05 AM, Mark Brown wrote: > > > [PATCH] ASoC: nau8825: apply BIQ to reduce recording signal DC offset > > This is hard to review since it's quite complex and doing things that > > look like they might be using general purpose parts of the chip for > > specialist purposes. > We find there is a DC offset issue when recording. For the issue, it > needs a HPF in ADC to reduce the offset, but no such hardware circuit. > Thus, the driver configures the biquard filter as HPF when headset > connected. It is a must setup for the codec. This patch sets the > coefficients A1, A2, B0, B1, and B3 in the biquad filter to make the > HPF funciton. I understand what it's doing but obviously a biquad filter isn't specialized for this function...
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