From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [78.32.30.218]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F1E373009C8 for ; Sun, 29 Mar 2026 09:40:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=78.32.30.218 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774777255; cv=none; b=s5wqI7fEa+7sSQIWfeS0LMuQIDEjR37npgTDf9ioClbEkJDuBDJV6Qb09Zd+4yEVM5Yr5HxcQiFB8H1ceCeWqElrG16CMGBa9/TMULpIg1qHTM1hqGozXDC6RtXESfwuPTTV6k01jxAyCM16f79Yu7uu6x5I1k2ZZCONzZ7VNl0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774777255; c=relaxed/simple; bh=X7sbKucCbl/JqdxspMjRfR/zWWx+5M7lhl/MNi5tH3I=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=TkW+H7wtpq0Mgrpy1UIYD87PT1BJRmwMpCFjErikweZDYIg46mMRfAka7WGff3zkl/BNcqvfsOYFu9sjHFEoN2XNKySEEGR6e4LSUm56NzWFpsu9208xTc6A4G9LsuOxhRrPjOirZu/15JYlA25QURq0p2OkKi51E9Rn1uT28ow= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk; spf=none smtp.mailfrom=armlinux.org.uk; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b=Jc2Py1MS; arc=none smtp.client-ip=78.32.30.218 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="Jc2Py1MS" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=VedDf6KjO7+dUX4YVKgtrHVL8jRFgWiX8TrdhyAcPls=; b=Jc2Py1MS/550Vpu9IWtlooDX44 a0y5FYBt2WATmyZfNO92STW5xUTWe20esS0KQaitLEMVxE5zzvgpVCe+rGXRGf0nKgcKhnzpfVP/8 HB0uIISrxjcnHVgMQgzk35Xa5LhZ7AVOgkHHiXLWa6PR3MI3d8M60nBpUUUnsM1nLJVlSxTcunyaC UvIW3GzBYgDtz87l1RA6s7K/U0JZjT/3yGHKm8hfd8cfCFOEyeZgAMmq8O+zKeDpSXU87fZR3V4IF 33/hmTlexM7N21VguQNH6cZXzpB+RcuGNjg8QNUS86npk/fjLmlUkbf0Nd77xQKRd1QkY0BOI2BdZ //cPxMQg==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:49578) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1w6mdT-000000007qA-0Mle; Sun, 29 Mar 2026 10:40:47 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.98.2) (envelope-from ) id 1w6mdP-000000001cj-2hQZ; Sun, 29 Mar 2026 10:40:43 +0100 Date: Sun, 29 Mar 2026 10:40:43 +0100 From: "Russell King (Oracle)" To: Andrew Lunn Cc: Alexandre Torgue , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , linux-arm-kernel@lists.infradead.org, linux-stm32@st-md-mailman.stormreply.com, netdev@vger.kernel.org, Ong Boon Leong , Paolo Abeni Subject: Re: [PATCH net-next 01/10] net: stmmac: fix TSO support when some channels have TBS available Message-ID: References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: Russell King (Oracle) On Sat, Mar 28, 2026 at 09:36:41PM +0000, Russell King (Oracle) wrote: > According to the STM32MP25xx manual, which is dwmac v5.3, TBS (time > based scheduling) is not permitted for channels which have hardware > TSO enabled. Intel's commit 5e6038b88a57 ("net: stmmac: fix TSO and > TBS feature enabling during driver open") concurs with this, but it > is incomplete. > > This commit avoids enabling TSO support on the channels which have > TBS available, which, as far as the hardware is concerned, means we > do not set the TSE bit in the DMA channel's transmit control register. > > However, the net device's features apply to all queues(channels), which > means these channels may still be handed TSO skbs to transmit, and the > driver will pass them to stmmac_tso_xmit(). This will generate the > descriptors for TSO, even though the channel has the TSE bit clear. > > Fix this by checking whether the queue(channel) has TBS available, > and if it does, fall back to software GSO support. This is sufficient for the immediate issue of fixing the patch below, but I think there's another issue that also needs fixing here. TSO requires the hardware to support checksum offload, and there is a comment in the driver: /* DWMAC IPs can be synthesized to support tx coe only for a few tx * queues. In that case, checksum offloading for those queues that don't * support tx coe needs to fallback to software checksum calculation. * * Packets that won't trigger the COE e.g. most DSA-tagged packets will * also have to be checksummed in software. */ So, it seems at the very least we need to add a check (in a subsequent patch) for priv->plat->tx_queues_cfg[queue].coe_unsupported to stmmac_channel_tso_permitted(). I'm also wondering about the stmmac_has_ip_ethertype() thing, which checks whether the skb can be checksummed by the hardware, and how that interacts with TSO, and whether that's yet another hole that needs plugging. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!