net: ag71xx: disable napi interrupts during probe

ag71xx_probe is registering ag71xx_interrupt as handler for gmac0/gmac1
interrupts. The handler is trying to use napi_schedule to handle the
processing of packets. But the netif_napi_add for this device is
called a lot later in ag71xx_probe.

It can therefore happen that a still running gmac0/gmac1 is triggering the
interrupt handler with a bit from AG71XX_INT_POLL set in
AG71XX_REG_INT_STATUS. The handler will then call napi_schedule and the
napi code will crash the system because the ag->napi is not yet
initialized.

The gmcc0/gmac1 must be brought in a state in which it doesn't signal a
AG71XX_INT_POLL related status bits as interrupt before registering the
interrupt handler. ag71xx_hw_start will take care of re-initializing the
AG71XX_REG_INT_ENABLE.

This will become relevant when dual GMAC devices get added here.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Link: https://patch.msgid.link/20240905194938.8453-8-rosenp@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/atheros/ag71xx.c b/drivers/net/ethernet/atheros/ag71xx.c
index e28a4b018b1189c9ed6eb52f0bdcbf2c2c8270ba..96a6189cc31e1d70e6375ee17036a2515eed7c3b 100644 (file)
--- a/drivers/net/ethernet/atheros/ag71xx.c
+++ b/drivers/net/ethernet/atheros/ag71xx.c
@@ -1850,6 +1850,12 @@ static int ag71xx_probe(struct platform_device *pdev)
        if (!ag->mac_base)
                return -ENOMEM;
 
+       /* ensure that HW is in manual polling mode before interrupts are
+        * activated. Otherwise ag71xx_interrupt might call napi_schedule
+        * before it is initialized by netif_napi_add.
+        */
+       ag71xx_int_disable(ag, AG71XX_INT_POLL);
+
        ndev->irq = platform_get_irq(pdev, 0);
        err = devm_request_irq(&pdev->dev, ndev->irq, ag71xx_interrupt,
                               0x0, dev_name(&pdev->dev), ndev);