[PATCH 4.9 185/223] powerpc/4xx/uic: clear pending interrupt after irq type/pol change

From: Greg Kroah-Hartman
Date: Fri Aug 02 2019 - 05:52:08 EST

[ Upstream commit 3ab3a0689e74e6aa5b41360bc18861040ddef5b1 ]

When testing out gpio-keys with a button, a spurious
interrupt (and therefore a key press or release event)
gets triggered as soon as the driver enables the irq
line for the first time.

This patch clears any potential bogus generated interrupt
that was caused by the switching of the associated irq's
type and polarity.

Signed-off-by: Christian Lamparter <chunkeey@xxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
arch/powerpc/sysdev/uic.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/sysdev/uic.c b/arch/powerpc/sysdev/uic.c
index a00949f3e378..a8ebc96dfed2 100644
--- a/arch/powerpc/sysdev/uic.c
+++ b/arch/powerpc/sysdev/uic.c
@@ -158,6 +158,7 @@ static int uic_set_irq_type(struct irq_data *d, unsigned int flow_type)

mtdcr(uic->dcrbase + UIC_PR, pr);
mtdcr(uic->dcrbase + UIC_TR, tr);
+ mtdcr(uic->dcrbase + UIC_SR, ~mask);

raw_spin_unlock_irqrestore(&uic->lock, flags);