On 24/09/20 8:27 am, Heiner Kallweit wrote:
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@alliedtelesis.co.nz Cc: stable@vger.kernel.org
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.
I'd be happy to send a follow-up to change IRQ_NONE to IRQ_HANDLED. I don't think the old code could have ever hit the IRQ_NONE (because event will always be non-zero) so it won't really be a change in behaviour. With the patch (that is now in spi/for-next) so far I do see a low number of spurious interrupts on the test setup where previously I would have seen failure to talk to the spi-flash.