linux-kernel - [PATCH v2 3/6] usb: typec: tipd: Add short-circuit for no irqs

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Date:   Thu, 23 Sep 2021 20:13:18 +0200
From:   Sven Peter <sven@...npeter.dev>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:     Sven Peter <sven@...npeter.dev>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Guido Günther <agx@...xcpu.org>,
        "Bryan O'Donoghue" <bryan.odonoghue@...aro.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Hector Martin <marcan@...can.st>,
        Mohamed Mediouni <mohamed.mediouni@...amail.com>,
        Stan Skowronek <stan@...ellium.com>,
        Mark Kettenis <mark.kettenis@...all.nl>,
        Alexander Graf <graf@...zon.com>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>
Subject: [PATCH v2 3/6] usb: typec: tipd: Add short-circuit for no irqs

If no interrupts are set in IntEventX directly skip to the end of the
interrupt handler and return IRQ_NONE instead of IRQ_HANDLED.
This possibly allows to detect spurious interrupts if the i2c bus is fast
enough.

Reviewed-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Signed-off-by: Sven Peter <sven@...npeter.dev>
---
changes since v1:
  - added Heikki's r-b
  - s/event/(event1 | event2)/

 drivers/usb/typec/tipd/core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/typec/tipd/core.c b/drivers/usb/typec/tipd/core.c
index 162d405baa92..cd1e37eb8a0c 100644
--- a/drivers/usb/typec/tipd/core.c
+++ b/drivers/usb/typec/tipd/core.c
@@ -476,6 +476,9 @@ static irqreturn_t tps6598x_interrupt(int irq, void *data)
 	}
 	trace_tps6598x_irq(event1, event2);
 
+	if (!(event1 | event2))
+		goto err_unlock;
+
 	if (!tps6598x_read_status(tps, &status))
 		goto err_clear_ints;
 
@@ -498,7 +501,9 @@ static irqreturn_t tps6598x_interrupt(int irq, void *data)
 err_unlock:
 	mutex_unlock(&tps->lock);
 
-	return IRQ_HANDLED;
+	if (event1 | event2)
+		return IRQ_HANDLED;
+	return IRQ_NONE;
 }
 
 static int tps6598x_check_mode(struct tps6598x *tps)
-- 
2.25.1