netdev - [PATCH net-next 1/2] can: sja1000: Prepare the use of a threaded handler

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Message-Id: <20230616134553.2786391-1-miquel.raynal@bootlin.com>
Date: Fri, 16 Jun 2023 15:45:52 +0200
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: Wolfgang Grandegger <wg@...ndegger.com>,
	Marc Kleine-Budde <mkl@...gutronix.de>,
	linux-can@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Eric Dumazet <edumazet@...gle.com>,
	netdev@...r.kernel.org,
	Sylvain Girard <sylvain.girard@...com>,
	Pascal Eberhard <pascal.eberhard@...com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	Herve Codina <herve.codina@...tlin.com>,
	Jérémie Dautheribes <jeremie.dautheribes@...tlin.com>,
	Miquel Raynal <miquel.raynal@...tlin.com>
Subject: [PATCH net-next 1/2] can: sja1000: Prepare the use of a threaded handler

In order to support a flavor of the sja1000 which sometimes freezes, it
will be needed upon certain interrupts to perform a soft reset. The soft
reset operation takes a bit of time, so better not do it within the hard
interrupt handler but rather in a threaded handler. Let's prepare the
possibility for sja1000_err() to request "interrupting" the current flow
and request the threaded handler to be run while keeping the interrupt
line low.

There is no functional change.

Signed-off-by: Miquel Raynal <miquel.raynal@...tlin.com>
---
 drivers/net/can/sja1000/sja1000.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/net/can/sja1000/sja1000.c b/drivers/net/can/sja1000/sja1000.c
index aac5956e4a53..4719806e3a9f 100644
--- a/drivers/net/can/sja1000/sja1000.c
+++ b/drivers/net/can/sja1000/sja1000.c
@@ -501,7 +501,8 @@ irqreturn_t sja1000_interrupt(int irq, void *dev_id)
 	struct sja1000_priv *priv = netdev_priv(dev);
 	struct net_device_stats *stats = &dev->stats;
 	uint8_t isrc, status;
-	int n = 0;
+	irqreturn_t ret = 0;
+	int n = 0, err;
 
 	if (priv->pre_irq)
 		priv->pre_irq(priv);
@@ -546,19 +547,23 @@ irqreturn_t sja1000_interrupt(int irq, void *dev_id)
 		}
 		if (isrc & (IRQ_DOI | IRQ_EI | IRQ_BEI | IRQ_EPI | IRQ_ALI)) {
 			/* error interrupt */
-			if (sja1000_err(dev, isrc, status))
+			err = sja1000_err(dev, isrc, status);
+			if (err)
 				break;
 		}
 		n++;
 	}
 out:
+	if (!ret)
+		ret = (n) ? IRQ_HANDLED : IRQ_NONE;
+
 	if (priv->post_irq)
 		priv->post_irq(priv);
 
 	if (n >= SJA1000_MAX_IRQ)
 		netdev_dbg(dev, "%d messages handled in ISR", n);
 
-	return (n) ? IRQ_HANDLED : IRQ_NONE;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(sja1000_interrupt);
 
-- 
2.34.1