Re: [PATCH v2] ASoC: meson: aiu: fifo-spdif: soft reset the S/PDIF datapath on start/stop

[Christian Hewitt <christianshewitt@gmail.com>]

> On 27 Jun 2026, at 5:08 pm, Ferass El Hafidi <funderscore@postmarketos.org> wrote:
> 
> Hi Christian,
> 
> On Sat, 27 Jun 2026 12:50, Christian Hewitt <christianshewitt@gmail.com> wrote:
>> The I2S FIFO soft-resets its fast domain on start (AIU_RST_SOFT bit 0 +
>> AIU_I2S_SYNC read in aiu_fifo_i2s_trigger), mirroring the downstream
>> vendor driver's audio_out_i2s_enable(). The S/PDIF FIFO has no equivalent:
>> it only toggles the IEC958 DCU, so a stale datapath FIFO can be replayed,
>> producing the "machine gun noise" buffer underrun - on start when switching
>> outputs, and on stop when playback ends. The latter is audible on devices
>> with an always-on S/PDIF-fed DAC (e.g. the ES7144 on the WeTek Play2).
>> 
>> The vendor driver resets the IEC958 fast domain (AIU_RST_SOFT bit 2) on
>> both enable and disable (audio_hw_958_enable), and when reconfiguring
>> (audio_hw_958_reset clears AIU_958_DCU_FF_CTRL then resets). Do the same:
>> reset before enabling the DCU on start, and after disabling it on stop.
>> 
>> Fixes: 6ae9ca9ce986bf ("ASoC: meson: aiu: add i2s and spdif support")
>> Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
> 
> You may have forgotten to add Martin's R-b here.

100%, but I also missed amending the commit description for the v2 change so
there’s a v3 where it’s been added. Sorry for the noise everyone, seems I am
a little out of practice at submitting things.

CH.