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Sun, 08 Feb 2026 17:35:43 -0800 (PST) Received: from gmail.com ([2a09:bac5:4e21:2705::3e3:36]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b8eda74a578sm326313766b.6.2026.02.08.17.35.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 08 Feb 2026 17:35:42 -0800 (PST) From: Qingfang Deng To: "Russell King (Oracle)" Cc: netdev@vger.kernel.org, Andrew Lunn , Jose Abreu , Maxime Chevallier , Thierry Reding , Paritosh Dixit Subject: Re: RFC: stmmac RSS support Date: Mon, 9 Feb 2026 09:35:25 +0800 Message-ID: <20260209013537.19052-1-dqfext@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Reference: Content-Transfer-Encoding: 8bit On Sat, 7 Feb 2026 17:36:06 +0000, Russell King (Oracle) wrote: > Hi, > > While looking at the possibilities of minimising the memory that > struct plat_stmmacenet_data consumes (880 bytes presently on > aarch64), I came across the RSS feature in stmmac. > > In commit 76067459c686 ("net: stmmac: Implement RSS and enable it in > XGMAC core"), support was added for RSS to the core stmmac driver for > the dwxgmac2 core. I can only find socfpga and tegra as the two > platform glues that use the dwxgmac2 core. > > RSS support is only enabled when both the core supports it, and the > platform glue sets priv->plat->rss_en. > > However, the stmmac-related results of grepping for this member do not > show any platform glues which set this flag: > > $ git grep '\' > Documentation/networking/device_drivers/ethernet/stmicro/stmmac.rst: int rss_en; > drivers/net/ethernet/stmicro/stmmac/stmmac_main.c: if (!priv->dma_cap.rssen || !priv->plat->rss_en) { > drivers/net/ethernet/stmicro/stmmac/stmmac_main.c: if (priv->dma_cap.rssen && priv->plat->rss_en) > > So, as no one has decided to enable this feature during the intervening > six years, is there any benefit to having this code in the mainline > kernel, or should this feature be dropped? > > If a user appears, the code will remain in git history and could be > restored. > > Thoughts? As someone who has worked on both DWC GMAC and DWC XGMAC, I think the whole XGMAC code needs to be uncoupled from the stmmac driver. They're completely different IP cores. > > -- > RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ > FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last! >