Applied "spi: bcm2835aux: ensure interrupts are enabled for shared handler" to the spi tree

[Mark Brown <broonie@xxxxxxxxxx>]

The patch

   spi: bcm2835aux: ensure interrupts are enabled for shared handler

has been applied to the spi tree at

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

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.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From bc519d9574618e47a0c788000fb78da95e18d953 Mon Sep 17 00:00:00 2001
From: Rob Herring <robh@xxxxxxxxxx>
Date: Thu, 3 May 2018 13:09:44 -0500
Subject: [PATCH] spi: bcm2835aux: ensure interrupts are enabled for shared
 handler

The BCM2835 AUX SPI has a shared interrupt line (with AUX UART).
Downstream fixes this with an AUX irqchip to demux the IRQ sources and a
DT change which breaks compatibility with older kernels. The AUX irqchip
was already rejected for upstream[1] and the DT change would break
working systems if the DTB is updated to a newer one. The latter issue
was brought to my attention by Alex Graf.

The root cause however is a bug in the shared handler. Shared handlers
must check that interrupts are actually enabled before servicing the
interrupt. Add a check that the TXEMPTY or IDLE interrupts are enabled.

[1] https://patchwork.kernel.org/patch/9781221/

Cc: Alexander Graf <agraf@xxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxx>
Cc: Eric Anholt <eric@xxxxxxxxxx>
Cc: Stefan Wahren <stefan.wahren@xxxxxxxx>
Cc: Florian Fainelli <f.fainelli@xxxxxxxxx>
Cc: Ray Jui <rjui@xxxxxxxxxxxx>
Cc: Scott Branden <sbranden@xxxxxxxxxxxx>
Cc: bcm-kernel-feedback-list@xxxxxxxxxxxx
Cc: linux-spi@xxxxxxxxxxxxxxx
Cc: linux-rpi-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
Reviewed-by: Eric Anholt <eric@xxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
 drivers/spi/spi-bcm2835aux.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c
index 1431cb98fe40..3094d818cf06 100644
--- a/drivers/spi/spi-bcm2835aux.c
+++ b/drivers/spi/spi-bcm2835aux.c
@@ -184,6 +184,11 @@ static irqreturn_t bcm2835aux_spi_interrupt(int irq, void *dev_id)
 	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
 	irqreturn_t ret = IRQ_NONE;
 
+	/* IRQ may be shared, so return if our interrupts are disabled */
+	if (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_CNTL1) &
+	      (BCM2835_AUX_SPI_CNTL1_TXEMPTY | BCM2835_AUX_SPI_CNTL1_IDLE)))
+		return ret;
+
 	/* check if we have data to read */
 	while (bs->rx_len &&
 	       (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) &
-- 
2.17.0

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