Re: [PATCH v2 1/3] spi: spi-fsl-dspi: Fix external abort on interrupt in exit paths

On Mon, Jun 15, 2020 at 03:56:01PM +0300, Vladimir Oltean wrote:

And the down-shot is that whatever is done in dspi_remove (free_irq) also needs to be done in dspi_suspend, but with extra care in dspi_resume not only to request the irq again, but also to flush the module's FIFOs and clear interrupts, because there might have been nasty stuff uncaught during sleep:

regmap_update_bits(dspi->regmap, SPI_MCR,
           SPI_MCR_CLR_TXF | SPI_MCR_CLR_RXF,
           SPI_MCR_CLR_TXF | SPI_MCR_CLR_RXF);
regmap_write(dspi->regmap, SPI_SR, SPI_SR_CLEAR);

So it's pretty messy.

It's a bit unusual to need to actually free the IRQ over suspend - what's driving that requirement here? I can see we might need to reinit the hardware but usually the interrupt handler can be left there safely.