[196] I2S: PSEL acquires GPIOs regardless of ENABLE

This anomaly applies to IC Rev. Revision 1, build codes CKAA-Cx0, QIAA-Cx0.

It was inherited from the previous IC revision Engineering C.

Symptoms

I2S controls GPIO even when I2S is not enabled.

Conditions

When using I2S->PSEL to configure GPIO.

Consequences

GPIO selected for I2S cannot be used for any other peripheral and will be configured as input.

Workaround

Do not rely on the pins selected in I2S->PSEL registers being free when I2S->ENABLE is set to DISABLE.

Only set the CONNECT bit in the I2S->PSEL registers to CONNECTED immediately before enabling I2S. When disabling I2S, set the CONNECT bit in the I2S->PSEL registers to DISCONNECTED.