Fix shared IRQ behavior in spi-fsl-dspi

This patch is taken out of the "Poll mode for NXP DSPI driver" series and respun against the "for-4.20" branch.
$(git describe --tags 13aed2392741) shows:
v4.20-rc1-18-g13aed2392741

Vladimir Oltean (1):
spi: spi-fsl-dspi: Exit the ISR with IRQ_NONE when it's not ours

 drivers/spi/spi-fsl-dspi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

2.17.1

The DSPI interrupt can be shared between two controllers at least on the LX2160A. In that case, the driver for one controller might misbehave and consume the other's interrupt. Fix this by actually checking if any of the bits in the status register have been asserted.

---
 drivers/spi/spi-fsl-dspi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

index 5e10dc5c93a5..6c2a30f9d85b 100644
@@ -874,9 +874,11 @@ static irqreturn_t dspi_interrupt(int irq, void *dev_id)
 					trans_mode);
 			}
 		}
+
+		return IRQ_HANDLED;
 	}
 
-	return IRQ_HANDLED;
+	return IRQ_NONE;
 }
 
 static const struct of_device_id fsl_dspi_dt_ids[] = {

2.17.1

The patch

spi: spi-fsl-dspi: Exit the ISR with IRQ_NONE when it's not ours

has been applied to the spi tree at

https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-5.3

All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted.

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Thanks,
Mark

From: Vladimir Oltean <[email protected]>
Date: Fri, 23 Aug 2019 00:24:50 +0300
Subject: [PATCH] spi: spi-fsl-dspi: Exit the ISR with IRQ_NONE when it's not
ours

The DSPI interrupt can be shared between two controllers at least on the LX2160A. In that case, the driver for one controller might misbehave and consume the other's interrupt. Fix this by actually checking if any of the bits in the status register have been asserted.

---
 drivers/spi/spi-fsl-dspi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

index 53335ccc98f6..545fc8189fb0 100644
@@ -886,9 +886,11 @@ static irqreturn_t dspi_interrupt(int irq, void *dev_id)
 					trans_mode);
 			}
 		}
+
+		return IRQ_HANDLED;
 	}
 
-	return IRQ_HANDLED;
+	return IRQ_NONE;
 }
 
 static const struct of_device_id fsl_dspi_dt_ids[] = {

2.20.1

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