4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Rob Herring <robh@xxxxxxxxxx> [ Upstream commit bc519d9574618e47a0c788000fb78da95e18d953 ] 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> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/spi/spi-bcm2835aux.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/drivers/spi/spi-bcm2835aux.c +++ b/drivers/spi/spi-bcm2835aux.c @@ -184,6 +184,11 @@ static irqreturn_t bcm2835aux_spi_interr 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) &
