Re: [PATCH] arm64: dts: imx8mp-debix-model-a: Disable EEE for 1000T

["Russell King (Oracle)" <linux@armlinux.org.uk>]

On Mon, Oct 27, 2025 at 09:27:49AM +0200, Laurent Pinchart wrote:
> I've tried to diagnose the issue by adding interrupt counters to
> dwmac4_irq_status(), counting interrupts for each bit of GMAC_INT_STATUS
> (0x00b0). Bit RGSMIIIS (0) is the only one that seems linked to the
> interrupts storm, increasing at around 10k per second. However, the
> corresponding bit in GMAC_INT_EN (0x00b4) is *not* set.

This is a change in the PCS series rather than the EEE series. It would
be good to narrow down whehn this problem appeared for you.

The RGSMIIIS bit set without RGSMIIIM (0x00b4 bit 0) shouldn't result
in an interrupt storm since the status will be masked. That doens't
mean that RGSMIIIS won't be set. So, at this point I'm not worried
about that.

Can you print the intr_status and intr_values in dwmac4_irq_status(),
maybe something like this:

	static int ctr = 0;

	if (ctr++ >= 9996) {
		printk("stmmac: INTS=%08x INTE=%08x\n", intr_status,
			intr_enable);

		if (ctr >= 10000)
			ctr = 0;
	}

        /* Discard disabled bits */
        intr_status &= intr_enable;

which should avoid too much noise during "normal" operation. It'll
print six consecutive interrupts every 10000.

> I ould suspect that the LPI RX exit interrupt is the one that fires
> constantly given its name, but I'm not sure how to test that.

You can check this because the LPI interrupts have statistic counter
associated with them. ethtool -S should give these, look for
lpi_mode_n.

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