linux-kernel - [PATCH 14/25] ASoC: meson: axg-pdm: introduce 'sysrate' property

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Date: Fri, 15 Mar 2024 02:21:50 +0300
From: Jan Dakinevich <jan.dakinevich@...utedevices.com>
To: Jan Dakinevich <jan.dakinevich@...utedevices.com>, Neil Armstrong
	<neil.armstrong@...aro.org>, Jerome Brunet <jbrunet@...libre.com>, Michael
 Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, Rob
 Herring <robh@...nel.org>, Krzysztof Kozlowski
	<krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>, Kevin Hilman <khilman@...libre.com>,
	Martin Blumenstingl <martin.blumenstingl@...glemail.com>, Liam Girdwood
	<lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, Linus Walleij
	<linus.walleij@...aro.org>, Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai
	<tiwai@...e.com>, <linux-amlogic@...ts.infradead.org>,
	<linux-clk@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
	<alsa-devel@...a-project.org>, <linux-sound@...r.kernel.org>,
	<linux-gpio@...r.kernel.org>
CC: <kernel@...utedevices.com>
Subject: [PATCH 14/25] ASoC: meson: axg-pdm: introduce 'sysrate' property

This driver unconditionally set the rate of DSP system clock to 250MHz,
that on A1 SoC family causes reconfiguring of 'hifi_pll' clock to some
rate, that is multiple to 250MHz.

Further, when playback is activating 'hifi_pll' would be reconfigured
to another rate to produce audio clock like 12288000Hz. Both these rates
can't coexist on same parent.

To avoid the fight for 'hifi_pll' clock allow PDM controller to
configure its maximum sysrate through device tree. It will allow to
inherit 'sysclk' from another clock (i.e. 'fclk_div2') and isolate
'hifi_pll' from PDM influence.

Signed-off-by: Jan Dakinevich <jan.dakinevich@...utedevices.com>
---
 sound/soc/meson/axg-pdm.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/sound/soc/meson/axg-pdm.c b/sound/soc/meson/axg-pdm.c
index d59050914d3c..a132444a51fb 100644
--- a/sound/soc/meson/axg-pdm.c
+++ b/sound/soc/meson/axg-pdm.c
@@ -94,6 +94,7 @@ struct axg_pdm {
 	struct clk *dclk;
 	struct clk *sysclk;
 	struct clk *pclk;
+	u32 sys_rate;
 };
 
 static void axg_pdm_enable(struct regmap *map)
@@ -172,10 +173,10 @@ static int axg_pdm_set_sysclk(struct axg_pdm *priv, unsigned int os,
 	 * the requested sample rate. In this case, the sample pointer
 	 * counter could overflow so set a lower system clock rate
 	 */
-	if (sys_rate < priv->cfg->sys_rate)
+	if (sys_rate < priv->sys_rate)
 		return clk_set_rate(priv->sysclk, sys_rate);
 
-	return clk_set_rate(priv->sysclk, priv->cfg->sys_rate);
+	return clk_set_rate(priv->sysclk, priv->sys_rate);
 }
 
 static int axg_pdm_set_sample_pointer(struct axg_pdm *priv)
@@ -386,7 +387,7 @@ static int axg_pdm_dai_probe(struct snd_soc_dai *dai)
 	 * sysclk must be set and enabled as well to access the pdm registers
 	 * Accessing the register w/o it will give a bus error.
 	 */
-	ret = clk_set_rate(priv->sysclk, priv->cfg->sys_rate);
+	ret = clk_set_rate(priv->sysclk, priv->sys_rate);
 	if (ret) {
 		dev_err(dai->dev, "setting sysclk failed\n");
 		goto err_pclk;
@@ -623,6 +624,9 @@ static int axg_pdm_probe(struct platform_device *pdev)
 	if (IS_ERR(priv->sysclk))
 		return dev_err_probe(dev, PTR_ERR(priv->sysclk), "failed to get dclk\n");
 
+	if (device_property_read_u32(dev, "sysrate", &priv->sys_rate))
+		priv->sys_rate = priv->cfg->sys_rate;
+
 	return devm_snd_soc_register_component(dev, &axg_pdm_component_drv,
 					       &axg_pdm_dai_drv, 1);
 }
-- 
2.34.1