On 04.09.2020 02:28, Chris Packham wrote:
> The SPIE register contains counts for the TX FIFO so any time the irq
> handler was invoked we would attempt to process the RX/TX fifos. Use the
> SPIM value to mask the events so that we only process interrupts that
> were expected.
>
> This was a latent issue exposed by commit 3282a3da25bd ("powerpc/64:
> Implement soft interrupt replay in C").
>
> Signed-off-by: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
>
> Notes:
> I've tested this on a T2080RDB and a custom board using the T2081 SoC. With
> this change I don't see any spurious instances of the "Transfer done but
> SPIE_DON isn't set!" or "Transfer done but rx/tx fifo's aren't empty!" messages
> and the updates to spi flash are successful.
>
> I think this should go into the stable trees that contain 3282a3da25bd but I
> haven't added a Fixes: tag because I think 3282a3da25bd exposed the issue as
> opposed to causing it.
>
> drivers/spi/spi-fsl-espi.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/spi/spi-fsl-espi.c b/drivers/spi/spi-fsl-espi.c
> index 7e7c92cafdbb..cb120b68c0e2 100644
> --- a/drivers/spi/spi-fsl-espi.c
> +++ b/drivers/spi/spi-fsl-espi.c
> @@ -574,13 +574,14 @@ static void fsl_espi_cpu_irq(struct fsl_espi *espi, u32 events)
> static irqreturn_t fsl_espi_irq(s32 irq, void *context_data)
> {
> struct fsl_espi *espi = context_data;
> - u32 events;
> + u32 events, mask;
>
> spin_lock(&espi->lock);
>
> /* Get interrupt events(tx/rx) */
> events = fsl_espi_read_reg(espi, ESPI_SPIE);
> - if (!events) {
> + mask = fsl_espi_read_reg(espi, ESPI_SPIM);
> + if (!(events & mask)) {
> spin_unlock(&espi->lock);
> return IRQ_NONE;
Sorry, I was on vacation and therefore couldn't comment earlier.
I'm fine with the change, just one thing could be improved IMO.
If we skip an unneeded interrupt now, then returning IRQ_NONE
causes reporting this interrupt as spurious. This isn't too nice
as spurious interrupts typically are seen as a problem indicator.
Therefore returning IRQ_HANDLED should be more appropriate.
This would just require a comment in the code explaining why we
do this, and why it can happen that we receive interrupts
we're not interested in.
> }
>
