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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Chien Nguyen <chien.nguyen.eb@rvc.renesas.com>,
        Chris Brandt <chris.brandt@renesas.com>,
        Wolfram Sang <wsa@the-dreams.de>
Subject: [PATCH 4.4 94/99] i2c: riic: Clear NACK in tend isr
Date:   Thu,  3 Oct 2019 17:53:57 +0200
Message-Id: <20191003154341.692437022@linuxfoundation.org>
In-Reply-To: <20191003154252.297991283@linuxfoundation.org>
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From: Chris Brandt <chris.brandt@renesas.com>

commit a71e2ac1f32097fbb2beab098687a7a95c84543e upstream.

The NACKF flag should be cleared in INTRIICNAKI interrupt processing as
description in HW manual.

This issue shows up quickly when PREEMPT_RT is applied and a device is
probed that is not plugged in (like a touchscreen controller). The result
is endless interrupts that halt system boot.

Fixes: 310c18a41450 ("i2c: riic: add driver")
Cc: stable@vger.kernel.org
Reported-by: Chien Nguyen <chien.nguyen.eb@rvc.renesas.com>
Signed-off-by: Chris Brandt <chris.brandt@renesas.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/i2c/busses/i2c-riic.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/i2c/busses/i2c-riic.c
+++ b/drivers/i2c/busses/i2c-riic.c
@@ -212,6 +212,7 @@ static irqreturn_t riic_tend_isr(int irq
 	if (readb(riic->base + RIIC_ICSR2) & ICSR2_NACKF) {
 		/* We got a NACKIE */
 		readb(riic->base + RIIC_ICDRR);	/* dummy read */
+		riic_clear_set_bit(riic, ICSR2_NACKF, 0, RIIC_ICSR2);
 		riic->err = -ENXIO;
 	} else if (riic->bytes_left) {
 		return IRQ_NONE;