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[94.59.215.181]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48066be77b5sm74577805e9.2.2026.01.27.11.08.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Jan 2026 11:08:42 -0800 (PST) From: "Anton D. Stavinskii" Date: Tue, 27 Jan 2026 23:08:19 +0400 Subject: [PATCH v2 1/2] ASoC: sophgo: cv1800b: document DAC overwrite handling Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260127-incremental-for-i2s-dvier-v2-1-5f66b841f63d@gmail.com> References: <20260127-incremental-for-i2s-dvier-v2-0-5f66b841f63d@gmail.com> In-Reply-To: <20260127-incremental-for-i2s-dvier-v2-0-5f66b841f63d@gmail.com> To: Liam Girdwood , Mark Brown , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Jaroslav Kysela , Takashi Iwai , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Chen Wang , Inochi Amaoto Cc: linux-sound@vger.kernel.org, sophgo@lists.linux.dev, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, "Anton D. Stavinskii" X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1769540916; l=1287; i=stavinsky@gmail.com; s=20260115; h=from:subject:message-id; bh=zadY22GSPVPhNTUtDV/+6Sluf6seV+Q8lASvyVpCmJ4=; b=rcy0EioZSDj08un85FD4cMTF4dOy7DTuSQ+7myJ0yfgsHFL4rCXoEjKKSGdM7eWN8MUM5J+1L rSTdu+GC0QwCHnuC5/qCHba9LWd4lsde4UUcAK/xj9+KiVKjYPcIw+f X-Developer-Key: i=stavinsky@gmail.com; a=ed25519; pk=2WxGZ1zd1vQwSPFCSks6zrADqUDBUdtq39lElk4ZE7Q= Add comments to cv1800b_dac_mute() and its caller to explain how the overwrite mechanism works and why we force it off before playback. Signed-off-by: Anton D. Stavinskii --- sound/soc/sophgo/cv1800b-sound-dac.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/sound/soc/sophgo/cv1800b-sound-dac.c b/sound/soc/sophgo/cv1800= b-sound-dac.c index ccf386174639..135322bcf6ad 100644 --- a/sound/soc/sophgo/cv1800b-sound-dac.c +++ b/sound/soc/sophgo/cv1800b-sound-dac.c @@ -57,6 +57,10 @@ static void cv1800b_dac_enable(struct cv1800b_priv *priv= , bool enable) writel(val, priv->regs + CV1800B_TXDAC_CTRL0); } =20 +/* + * Control the DAC overwrite bits. When enabled, the DAC outputs the fixed + * overwrite value instead of samples from the I2S input. + */ static void cv1800b_dac_mute(struct cv1800b_priv *priv, bool enable) { u32 val; @@ -105,7 +109,7 @@ static int cv1800b_dac_hw_params(struct snd_pcm_substre= am *substream, dev_err(priv->dev, "rate %u is not supported\n", rate); return -EINVAL; } - + /* Clear DAC overwrite so playback uses I2S data. */ cv1800b_dac_mute(priv, false); /* minimal decimation for 48kHz is 64*/ ret =3D cv1800b_dac_decimation(priv, DECIMATION_64); --=20 2.43.0