On 2024-08-07 18:27:03 [+0200], Jerome Brunet wrote:
With PREEMPT_RT enabled a spinlock_t becomes a sleeping lock.
This is usually not a problem with spinlocks used in IRQ context since IRQ handlers get threaded. However, if IRQF_ONESHOT is set, the primary handler won't be force-threaded and runs always in hardirq context. This is a problem because spinlock_t requires a preemptible context on PREEMPT_RT.
In this particular instance, regmap mmio uses spinlock_t to protect the register access and IRQF_ONESHOT is set on the IRQ. In this case, it is actually better to do everything in threaded handler and it solves the problem with PREEMPT_RT.
Reported-by: Arseniy Krasnov avkrasnov@salutedevices.com Closes: https://lore.kernel.org/linux-amlogic/20240729131652.3012327-1-avkrasnov@sal... Suggested-by: Sebastian Andrzej Siewior bigeasy@linutronix.de Fixes: b11d26660dff ("ASoC: meson: axg-fifo: use threaded irq to check periods") Signed-off-by: Jerome Brunet jbrunet@baylibre.com
Reviewed-by: Sebastian Andrzej Siewior bigeasy@linutronix.de
Sebastian