4.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Rob Herring robh@kernel.org
[ 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@suse.de Cc: Marc Zyngier marc.zyngier@arm.com Cc: Mark Brown broonie@kernel.org Cc: Eric Anholt eric@anholt.net Cc: Stefan Wahren stefan.wahren@i2se.com Cc: Florian Fainelli f.fainelli@gmail.com Cc: Ray Jui rjui@broadcom.com Cc: Scott Branden sbranden@broadcom.com Cc: bcm-kernel-feedback-list@broadcom.com Cc: linux-spi@vger.kernel.org Cc: linux-rpi-kernel@lists.infradead.org Cc: linux-arm-kernel@lists.infradead.org Signed-off-by: Rob Herring robh@kernel.org Reviewed-by: Eric Anholt eric@anholt.net Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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) &