[alsa-devel] Pop and offsets at start of audio playback/record for SGTL5000 on i.MX28

[Craig McQueen]

On 14/11/14 13:04, Michael Trimarchi wrote:
>
> Hi
>
> Il 14/nov/2014 09:58 "Craig McQueen" 
> <craig.mcqueen at beamcommunications.com 
> <mailto:craig.mcqueen at beamcommunications.com>> ha scritto:
> >
> > On 14/11/14 12:45, Michael Trimarchi wrote:
> >>
> >> Hi
> >>
> >> Il 14/nov/2014 09:44 "Craig McQueen" 
> <craig.mcqueen at beamcommunications.com 
> <mailto:craig.mcqueen at beamcommunications.com>> ha scritto:
> >> >
> >> > I'm testing the 3.14.19 kernel for i.MX28 EVK, which has an 
> SGTL5000 CODEC. I've also tested on the 3.18-rc4 kernel and confirmed 
> this issue still occurs.
> >> >
> >>
> >> Are you using it in master or slave mode?
> >
> >
>
> Try to change the pin mux of data line in order to be hz in idle mode 
> and add a small pull down resistor. Can you check if the dataline is 
> up when clocks go off?
>

Is it the I2S_DIN pin you're referring to?

This is the Freescale i.MX28 EVK we're talking about, so it's best to 
have a software fix that works on the stock EVK hardware. I'm checking 
the schematics and I don't see a pull-down. The following is in the 
imx28.dtsi device tree source:

                 saif0_pins_b: saif0 at 1 {
                     reg = <1>;
                     fsl,pinmux-ids = <
                         MX28_PAD_SAIF0_LRCLK__SAIF0_LRCLK
                         MX28_PAD_SAIF0_BITCLK__SAIF0_BITCLK
                         MX28_PAD_SAIF0_SDATA0__SAIF0_SDATA0
                     >;
                     fsl,drive-strength = <MXS_DRIVE_12mA>;
                     fsl,voltage = <MXS_VOLTAGE_HIGH>;
                     fsl,pull-up = <MXS_PULL_ENABLE>;
                 };

However on the i.MX28 I don't think the SAIF0_SDATA0 pin actually has a 
pull-up (only a few pins do).

Anyway, I will look into that soon.

-- 
Craig McQueen