RE: [PATCH 2/4] ASoC: wm8994: don't lose the AIF clock ratio when staying at 32kHz SYSCLK

["Sylwester Nawrocki" <s.nawrocki@samsung.com>]

> -----Original Message-----
> From: Marek Szyprowski <m.szyprowski@samsung.com>
> Sent: środa, 21 października 2026 12:18
> Cc: Marek Szyprowski <m.szyprowski@samsung.com>; Liam Girdwood
> <lgirdwood@gmail.com>; Mark Brown <broonie@kernel.org>; Sylwester
> Nawrocki <s.nawrocki@samsung.com>; Charles Keepax
> <ckeepax@opensource.cirrus.com>; Krzysztof Kozlowski <krzk@kernel.org>;
> Simon Shields <simon@lineageos.org>; Artur Weber
> <aweber.kernel@gmail.com>; patches@opensource.cirrus.com; linux-
> sound@vger.kernel.org
> Subject: [PATCH 2/4] ASoC: wm8994: don't lose the AIF clock ratio when
> staying at 32kHz SYSCLK
> 
> When SYSCLK drops below 50kHz, the AIFnCLK rate ratio is saved and
> temporarily lowered to 128fs for accessory detection, then restored
> once SYSCLK gets fast enough again. The ratio is however saved again
> on each clock reconfiguration done while SYSCLK is still slow, which
> overwrites the original ratio with the 128fs one.
> 
> This happens on the Exynos4412 Trats2 board, which set MCLK2 as SYSCLK
> twice during the card probe and then configure FLL1 while still running
> from MCLK2. Once SYSCLK is switched to FLL1, the 128fs ratio is
> "restored", so AIF1 is left configured for 48kHz at 128fs while being
> clocked at 256fs. If any digital path is powered up before a stream
> reconfigures the AIF, the codec raises FIFO error interrupts every
> 10ms, flooding the kernel log:
> 
>  wm8994-codec wm8994-codec: FIFO error
> 
> Save the original ratio only when entering the low SYSCLK mode. While
> at it, move the code duplicated in _wm8994_set_fll() and
> wm8994_set_dai_sysclk() to a common helper.
> 
> Fixes: 6730049a4763 ("ASoC: wm8994: Lower AIFnCLK divisor when
> dropping to 32kHz")
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>