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

From: Ferass El Hafidi <funderscore@postmarketos.org>
To: linux-amlogic@lists.infradead.org,
	Christian Hewitt <christianshewitt@gmail.com>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>, Jaroslav Kysela <perex@perex.cz>,
	Takashi Iwai <tiwai@suse.com>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Kevin Hilman <khilman@baylibre.com>,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	linux-sound@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] ASoC: meson: aiu: fifo-spdif: soft reset the S/PDIF datapath on start/stop
Date: Sat, 27 Jun 2026 13:08:06 +0000	[thread overview]
Message-ID: <thanni.i9bbkrc1oza2@postmarketos.org> (raw)
In-Reply-To: <20260627125030.808058-1-christianshewitt@gmail.com>

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.

Best regards,
Ferass