ASoC: stm32: sai: manage context in set_sysclk callback

The mclk direction now needs to be specified in endpoint node with
"system-clock-direction-out" property. However some calls to the
set_sysclk callback, related to CPU DAI clock, result in unbalanced
calls to clock API.
The set_sysclk callback in STM32 SAI driver is intended only for mclk
management. So it is relevant to ensure that calls to set_sysclk are
related to mclk only.
Since the master clock is handled only at runtime, skip the calls to
set_sysclk in the initialization phase.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Link: https://patch.msgid.link/20250916123118.84175-1-olivier.moysan@foss.st.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Olivier Moysan

sound/soc/stm/stm32_sai_sub.c

@@ -672,6 +672,14 @@ static int stm32_sai_set_sysclk(struct snd_soc_dai *cpu_dai,
 	struct stm32_sai_sub_data *sai = snd_soc_dai_get_drvdata(cpu_dai);
 	int ret;
 
+	/*
+	 * The mclk rate is determined at runtime from the audio stream rate.
+	 * Skip calls to the set_sysclk callback that are not relevant during the
+	 * initialization phase.
+	 */
+	if (!snd_soc_card_is_instantiated(cpu_dai->component->card))
+		return 0;
+
 	if (dir == SND_SOC_CLOCK_OUT && sai->sai_mclk) {
 		ret = stm32_sai_sub_reg_up(sai, STM_SAI_CR1_REGX,
 					   SAI_XCR1_NODIV,