linux-kernel - [PATCH 2/2] ASoC: stm32: sai: add a check on minimal kernel frequency

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Message-ID: <20250430165210.321273-3-olivier.moysan@foss.st.com>
Date: Wed, 30 Apr 2025 18:52:09 +0200
From: Olivier Moysan <olivier.moysan@...s.st.com>
To: Olivier Moysan <olivier.moysan@...s.st.com>,
        Arnaud Pouliquen
	<arnaud.pouliquen@...s.st.com>,
        Liam Girdwood <lgirdwood@...il.com>, Mark
 Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai
	<tiwai@...e.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre
 Torgue <alexandre.torgue@...s.st.com>
CC: <linux-sound@...r.kernel.org>, <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/2] ASoC: stm32: sai: add a check on minimal kernel frequency

On MP2 SoCs SAI kernel clock rate is managed through
stm32_sai_set_parent_rate() function.
If the kernel clock rate was set previously to a low frequency, this
frequency may be too low to support the newly requested audio stream rate.
However the stm32_sai_rate_accurate() will only check accuracy against
the maximum kernel clock rate. The function will return leaving the kernel
clock rate unchanged.
Add a check on minimal frequency requirement, to avoid this.

Fixes: b1d2e4067dc6 ("ASoC: stm32: sai: add stm32mp25 support")
Signed-off-by: Olivier Moysan <olivier.moysan@...s.st.com>
---
 sound/soc/stm/stm32_sai_sub.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sound/soc/stm/stm32_sai_sub.c b/sound/soc/stm/stm32_sai_sub.c
index 4d018b4bc3f0..bf5299ba11c3 100644
--- a/sound/soc/stm/stm32_sai_sub.c
+++ b/sound/soc/stm/stm32_sai_sub.c
@@ -447,7 +447,10 @@ static int stm32_sai_set_parent_rate(struct stm32_sai_sub_data *sai,
 	 * return immediately.
 	 */
 	sai_curr_rate = clk_get_rate(sai->sai_ck);
-	if (stm32_sai_rate_accurate(sai_ck_max_rate, sai_curr_rate))
+	dev_dbg(&pdev->dev, "kernel clock rate: min [%u], max [%u], current [%u]",
+		sai_ck_min_rate, sai_ck_max_rate, sai_curr_rate);
+	if (stm32_sai_rate_accurate(sai_ck_max_rate, sai_curr_rate) &&
+	    sai_curr_rate >= sai_ck_min_rate)
 		return 0;
 
 	/*
-- 
2.25.1