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From: Serge Semin <fancer.lancer@gmail.com>
To: Russell King <linux@armlinux.org.uk>,
	Alexandre Torgue <alexandre.torgue@foss.st.com>,
	Jose Abreu <joabreu@synopsys.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	John Fastabend <john.fastabend@gmail.com>,
	bpf@vger.kernel.org,
	netdev@vger.kernel.org,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH RFC net-next 1/3] net: stmmac: Prevent RGSMIIIS IRQs flood
Date: Sat, 25 May 2024 00:02:57 +0300
Message-ID: <20240524210304.9164-1-fancer.lancer@gmail.com>
In-Reply-To: <ZkDuJAx7atDXjf5m@shell.armlinux.org.uk>
References: <ZkDuJAx7atDXjf5m@shell.armlinux.org.uk>
Precedence: bulk
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Without reading the GMAC_RGSMIIIS/MAC_PHYIF_Control_Status the IRQ line
won't be de-asserted causing interrupt handler executed over and over. As
a quick-fix let's just dummy-read the CSR for now.

Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c | 2 ++
 drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c    | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
index adb872d5719f..2ae8467c588e 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
@@ -304,6 +304,8 @@ static int dwmac1000_irq_status(struct mac_device_info *hw,
 	dwmac_pcs_isr(ioaddr, GMAC_PCS_BASE, intr_status, x);
 
 	if (intr_status & PCS_RGSMIIIS_IRQ) {
+		/* TODO Dummy-read to clear the IRQ status */
+		readl(ioaddr + GMAC_RGSMIIIS);
 		phylink_pcs_change(&hw->mac_pcs, false);
 		x->irq_rgmii_n++;
 	}
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
index a892d361a4e4..cd2ca1d0222c 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
@@ -896,6 +896,8 @@ static int dwmac4_irq_status(struct mac_device_info *hw,
 
 	dwmac_pcs_isr(ioaddr, GMAC_PCS_BASE, intr_status, x);
 	if (intr_status & PCS_RGSMIIIS_IRQ) {
+		/* TODO Dummy-read to clear the IRQ status */
+		readl(ioaddr + GMAC_PHYIF_CONTROL_STATUS);
 		phylink_pcs_change(&hw->mac_pcs, false);
 		x->irq_rgmii_n++;
 	}
-- 
2.43.0