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spi: bcm2835aux: ensure interrupts are enabled for shared handler

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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 <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Eric Anholt <[email protected]>
Cc: Stefan Wahren <[email protected]>
Cc: Florian Fainelli <[email protected]>
Cc: Ray Jui <[email protected]>
Cc: Scott Branden <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Rob Herring <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>
Signed-off-by: Mark Brown <[email protected]>
This commit is contained in:
Rob Herring 2018-05-03 13:09:44 -05:00 • committed by Mark Brown
commit bc519d9574
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5
drivers/spi/spi-bcm2835aux.c
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@ -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) &