linux-kernel - [PATCH AUTOSEL 4.4 23/35] powerpc/4xx/uic: clear pending interrupt after irq type/pol change

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Message-Id: <20190719041423.19322-23-sashal@kernel.org>
Date:   Fri, 19 Jul 2019 00:14:11 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Christian Lamparter <chunkeey@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Sasha Levin <sashal@...nel.org>, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH AUTOSEL 4.4 23/35] powerpc/4xx/uic: clear pending interrupt after irq type/pol change

From: Christian Lamparter <chunkeey@...il.com>

[ 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@...il.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 6893d8f236df..225346dda151 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);
 
-- 
2.20.1