[alsa-devel] ASoC: sgtl5000: SMALL_POP and loud click noise 5 secs after playback stopped

[Clemens Gruber]

Hi,

since commit b101acfabc9377469af3abfb7cb63112da367284 I can hear a loud
click / pop noise, always occuring 5 seconds after playback stopped.

Hardware: i.MX6Q board with SGTL5000
Kernel: 4.7-rc2 master

In the commit history of sgtl5000.h I saw that SGTL5000_SMALL_POP was
previously 0 and that Fabio, who changed it to 0, had a similar problem
back then. Now with SGTL5000_SMALL_POP at 1, the problem reappeared.
Changing it back to 0 fixes the problem for me, but as Axel Lin
explained in the commit mentioned above, having 0 as mask leads to not
writing anything to the CHIP_REF_CTRL register and the SMALL_POP bit
stays as it was.

So why does this help?

Maybe having SMALL_POP active causes that noise in some circumstances?
Then we could add a devicetree property to turn it on or off as needed.

Or, the documentation of the SMALL_POP bit in the datasheet is not
correct / inverted? Then we could remove that write to the CHIP_REF_CTRL
register and leave the SMALL_POP bit at its default value?


Axel: Did changing SGTL5000_SMALL_POP to 1 remove a click/pop noise on
your board or did you just notice the error with the mask argument of
snd_soc_update_bits and fixed it?

Thanks,
Clemens