linux-kernel - [PATCH 06/15] can: m_can: Avoid reading irqstatus twice

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Date:   Wed, 16 Nov 2022 21:52:59 +0100
From:   Markus Schneider-Pargmann <msp@...libre.com>
To:     Chandrasekar Ramakrishnan <rcsekar@...sung.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        Wolfgang Grandegger <wg@...ndegger.com>
Cc:     linux-can@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Markus Schneider-Pargmann <msp@...libre.com>
Subject: [PATCH 06/15] can: m_can: Avoid reading irqstatus twice

For peripheral devices the m_can_rx_handler is called directly after
setting cdev->irqstatus. This means we don't have to read the irqstatus
again in m_can_rx_handler. Avoid this by adding a parameter that is
false for direct calls.

Signed-off-by: Markus Schneider-Pargmann <msp@...libre.com>
---
 drivers/net/can/m_can/m_can.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 5c00c6162058..0efa6dee0617 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -896,14 +896,13 @@ static int m_can_handle_bus_errors(struct net_device *dev, u32 irqstatus,
 	return work_done;
 }
 
-static int m_can_rx_handler(struct net_device *dev, int quota)
+static int m_can_rx_handler(struct net_device *dev, int quota, u32 irqstatus)
 {
 	struct m_can_classdev *cdev = netdev_priv(dev);
 	int rx_work_or_err;
 	int work_done = 0;
-	u32 irqstatus, psr;
+	u32 psr;
 
-	irqstatus = cdev->irqstatus | m_can_read(cdev, M_CAN_IR);
 	if (!irqstatus)
 		goto end;
 
@@ -947,12 +946,12 @@ static int m_can_rx_handler(struct net_device *dev, int quota)
 	return work_done;
 }
 
-static int m_can_rx_peripheral(struct net_device *dev)
+static int m_can_rx_peripheral(struct net_device *dev, u32 irqstatus)
 {
 	struct m_can_classdev *cdev = netdev_priv(dev);
 	int work_done;
 
-	work_done = m_can_rx_handler(dev, NAPI_POLL_WEIGHT);
+	work_done = m_can_rx_handler(dev, NAPI_POLL_WEIGHT, irqstatus);
 
 	/* Don't re-enable interrupts if the driver had a fatal error
 	 * (e.g., FIFO read failure).
@@ -968,8 +967,11 @@ static int m_can_poll(struct napi_struct *napi, int quota)
 	struct net_device *dev = napi->dev;
 	struct m_can_classdev *cdev = netdev_priv(dev);
 	int work_done;
+	u32 irqstatus;
+
+	irqstatus = cdev->irqstatus | m_can_read(cdev, M_CAN_IR);
 
-	work_done = m_can_rx_handler(dev, quota);
+	work_done = m_can_rx_handler(dev, quota, irqstatus);
 
 	/* Don't re-enable interrupts if the driver had a fatal error
 	 * (e.g., FIFO read failure).
@@ -1080,7 +1082,7 @@ static irqreturn_t m_can_isr(int irq, void *dev_id)
 		m_can_disable_all_interrupts(cdev);
 		if (!cdev->is_peripheral)
 			napi_schedule(&cdev->napi);
-		else if (m_can_rx_peripheral(dev) < 0)
+		else if (m_can_rx_peripheral(dev, ir) < 0)
 			goto out_fail;
 	}
 
-- 
2.38.1