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From:   Chris Packham <chris.packham@alliedtelesis.co.nz>
To:     broonie@kernel.org, npiggin@gmail.com, hkallweit1@gmail.com
Cc:     linux-spi@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-kernel@vger.kernel.org,
        Chris Packham <chris.packham@alliedtelesis.co.nz>,
        stable@vger.kernel.org
Subject: [PATCH] spi: fsl-espi: Only process interrupts for expected events
Date:   Fri,  4 Sep 2020 12:28:12 +1200
Message-Id: <20200904002812.7300-1-chris.packham@alliedtelesis.co.nz>
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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.
   =20
    I think this should go into the stable trees that contain 3282a3da25b=
d but I
    haven't added a Fixes: tag because I think 3282a3da25bd exposed the i=
ssue 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 =3D context_data;
-	u32 events;
+	u32 events, mask;
=20
 	spin_lock(&espi->lock);
=20
 	/* Get interrupt events(tx/rx) */
 	events =3D fsl_espi_read_reg(espi, ESPI_SPIE);
-	if (!events) {
+	mask =3D fsl_espi_read_reg(espi, ESPI_SPIM);
+	if (!(events & mask)) {
 		spin_unlock(&espi->lock);
 		return IRQ_NONE;
 	}
--=20
2.28.0