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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Maxime Coquelin , Alexandre Torgue Cc: Jose Abreu , EricChan , Simon Horman , zhangpengfei16@xiaomi.com, netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net] net: stmmac: xgmac: do not treat TBU as a TX event Date: Wed, 14 Oct 2026 12:56:07 +0800 Message-ID: <20261014045607.3421104-1-zhangfeionline@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <179194881415.434549.5017437610608933310@kernel.org> References: <179194881415.434549.5017437610608933310@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit > [Severity: Medium] > Can the XDP_TX and ndo_xdp_xmit path stall permanently on XGMAC in > shared-IRQ mode when the TX coalesce timer is disabled? This is not caused by this patch. It needs a very specific setup: XDP TX traffic, tx-usecs set to 0, and tx-frames too large to be reached below STMMAC_TX_THRESH. With that setup the same stall can already happen on XGMAC with per-channel MSI today, because stmmac_xdp_xmit_xdpf() only sets IC on a tx_coal_frames boundary and has no fallback when the TX timer is disabled. I will look at fixing that in the XDP TX path with a separate patch, but it is independent of this one. > [Severity: Medium] > This isn't a bug introduced by this patch, but does > dwmac4_dma_interrupt() in dwmac4_lib.c have the same sticky TBU > problem? Yes, it looks like it does, especially since commit 6ccf12ae111e ("net: stmmac: use interrupt mode INTM=1 for multi-MSI") moved the TBU check out of the NIS block. I only have XGMAC hardware at the moment, so I kept this patch to XGMAC. I will send a separate patch for dwmac4 once I can test it on dwmac4 hardware.