From: Olivier Moysan olivier.moysan@foss.st.com
[ Upstream commit 27fa1a8b2803dfd88c39f03b0969c55f667cdc43 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org ---
LLM Generated explanations, may be completely bogus:
YES - Guarding `stm32_sai_set_sysclk()` until the card is instantiated (`sound/soc/stm/stm32_sai_sub.c:675-681`) prevents the early simple- card `init` call (`sound/soc/generic/simple-card-utils.c:571`) from programming clocks before runtime. - That init-time call currently triggers a second `clk_rate_exclusive_get()` on the shared SAI kernel clock (`sound/soc/stm/stm32_sai_sub.c:442`) and another `clk_set_rate_exclusive()` on the MCLK (`sound/soc/stm/stm32_sai_sub.c:709`) before any matching “0 Hz” teardown happens; at shutdown we only drop one reference (`sound/soc/stm/stm32_sai_sub.c:692-702`), leaving the clocks permanently locked and causing later `-EBUSY` failures. - The regression shows up as soon as boards tag the CPU endpoint with `system-clock-direction-out` (parsed in `simple-card-utils.c:290` and already present in ST’s shipping DTs such as `arch/arm/boot/dts/st/stm32mp15xx-dkx.dtsi:520`), a configuration encouraged since commit 5725bce709db; the exclusive clock management added in 2cfe1ff22555 made the imbalance fatal. - The fix is minimal and contained: it simply skips the init-phase invocation for a driver that already derives MCLK from the stream rate, so the risk of regressions is low while it resolves a real runtime bug on current hardware.
sound/soc/stm/stm32_sai_sub.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/sound/soc/stm/stm32_sai_sub.c b/sound/soc/stm/stm32_sai_sub.c index 463a2b7d023b9..0ae1eae2a59e2 100644 --- a/sound/soc/stm/stm32_sai_sub.c +++ b/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,