From: Heiner Kallweit <hkallweit1@gmail.com>
To: Chris Packham <chris.packham@alliedtelesis.co.nz>,
broonie@kernel.org, npiggin@gmail.com
Cc: linux-spi@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] spi: fsl-espi: Only process interrupts for expected events
Date: Wed, 23 Sep 2020 22:27:33 +0200 [thread overview]
Message-ID: <ec77cf82-5ef1-c650-3e8a-80be749c2214@gmail.com> (raw)
In-Reply-To: <20200904002812.7300-1-chris.packham@alliedtelesis.co.nz>
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.
> }
>
next prev parent reply other threads:[~2020-09-23 20:27 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-04 0:28 [PATCH] spi: fsl-espi: Only process interrupts for expected events Chris Packham
2020-09-13 22:03 ` Chris Packham
2020-09-14 2:28 ` Nicholas Piggin
2020-09-14 9:06 ` Joakim Tjernlund
2020-09-21 21:40 ` Mark Brown
2020-09-23 20:27 ` Heiner Kallweit [this message]
2020-09-23 21:01 ` Chris Packham
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