On Mon, May 12, 2025 at 11:17:48AM +0200, Geert Uytterhoeven wrote:
On Fri, 9 May 2025 at 16:18, Francesco Dolcini francesco@dolcini.it wrote:
If an input changes state during wake-up and is used as an interrupt source, the IRQ handler reads the volatile input register to clear the interrupt mask and deassert the IRQ line. However, the IRQ handler is triggered before access to the register is granted, causing the read operation to fail.
As a result, the IRQ handler enters a loop, repeatedly printing the "failed reading register" message, until `pca953x_resume` is eventually called, which restores the driver context and enables access to registers.
Fix by disabling the IRQ line before entering suspend mode, and re-enabling it after the driver context is restored in `pca953x_resume`.
An irq can be disabled with disable_irq() and still wake the system as long as the irq has wake enabled, so the wake-up functionality is preserved.
...
While this does not cause the regression seen on Salvator-XS with the earlier approach[1], I expect this will break using a GPIO as a wake-up source?
Good point! Have this code been checked for that kind of scenarios?
[1] https://lore.kernel.org/linux-gpio/CAMuHMdVnKX23yi7ir1LVxfXAMeeWMFzM+cdgSSTN...