[PATCH 3.16 47/72] i2c: riic: Clear NACK in tend isr

From: Ben Hutchings
Date: Sun Dec 08 2019 - 08:56:43 EST

3.16.79-rc1 review patch. If anyone has any objections, please let me know.


From: Chris Brandt <chris.brandt@xxxxxxxxxxx>

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")
Reported-by: Chien Nguyen <chien.nguyen.eb@xxxxxxxxxxxxxxx>
Signed-off-by: Chris Brandt <chris.brandt@xxxxxxxxxxx>
Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
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;