From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay7-d.mail.gandi.net (relay7-d.mail.gandi.net [217.70.183.200]) (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 EAF02293C6F; Fri, 27 Jun 2025 09:09:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.183.200 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751015391; cv=none; b=J3GLvFm6OZLgSBa8+zt66bK15m1loI0mGML7qdGA+V7Jo0fVZagw79bI7uDoYrMbJOYxy6rL8JDRSTWywduRkFLk5RlmKEAwEt+u/pvUvdSCyx8Nukcjx3i8Yx6YWfkx5dbtLic4ZLmexYlOGUvZYJxIdmcUo32bFaqVMeIu9i0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751015391; c=relaxed/simple; bh=KII5Ba2qPN3Eo5AdFMv6pLbs0WUZsl4LhG8ZvSWtq9k=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=Vu5G8rpWXSOoGZYlAjXwhkWAiZYPZURtR81t0y5a1qAwy5AoaD6nm4Lk7e5fq5pyd+375RwlIOKzSRnGE7a2QlciLsvx4KWf01aeolYymTp/nsmd8eLl4ADmiBIajjX1xb8Q6pEw7F4XxtzbivORsIrJIMQQqOK+FNTHRwRyj14= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=mFfQKfcl; arc=none smtp.client-ip=217.70.183.200 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="mFfQKfcl" Received: by mail.gandi.net (Postfix) with ESMTPSA id 2E8DE4390F; Fri, 27 Jun 2025 09:09:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1751015387; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=A9uNp3pSOKOY+7xgQJRed4d6tQE1Z/95H/ytYVA1aP4=; b=mFfQKfcl3D2l0CX/M/DsMOqgQmKpCXiZkVzEjyLaRhOl/YgLbjCSWTaB1hfkHECCNwKPcG 49FfsPx8P/Davx9QVxGaPqNEYI+aXrJnMG1LjCAKxUmmL3Soj3HI9qrg4z/qi5RsT6mIT8 YgkZkoVtzAHbpughCfOuT5/PF0A9eQgOjmiKE3SBqcmSRs8LExew9WAWjS3yKFSwnatuAP a2FiL8Mv+xEu29f17MonAjiDUn3SUS8UaLP3ByKDbBXPjaNqxi5zwqJ8CvqlfJuA2pnP8Y emvqE2PaPO+HsD8IXD6PTSgNt4Cmm94LSYhbDZznbaXo+z89I/SS66u8mFBfog== From: =?utf-8?q?Th=C3=A9o_Lebrun?= Date: Fri, 27 Jun 2025 11:08:58 +0200 Subject: [PATCH net-next v2 12/18] net: macb: match skb_reserve(skb, NET_IP_ALIGN) with HW alignment Precedence: bulk X-Mailing-List: linux-mips@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Message-Id: <20250627-macb-v2-12-ff8207d0bb77@bootlin.com> References: <20250627-macb-v2-0-ff8207d0bb77@bootlin.com> In-Reply-To: <20250627-macb-v2-0-ff8207d0bb77@bootlin.com> To: Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Nicolas Ferre , Claudiu Beznea , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Samuel Holland , Richard Cochran , Russell King , Thomas Bogendoerfer , Vladimir Kondratiev , Gregory CLEMENT , Cyrille Pitchen , Harini Katakam , Rafal Ozieblo , Haavard Skinnemoen , Jeff Garzik Cc: netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, linux-mips@vger.kernel.org, Thomas Petazzoni , Tawfik Bayouk , =?utf-8?q?Th=C3=A9o_Lebrun?= X-Mailer: b4 0.14.2 X-GND-State: clean X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeeffedrtdefgddvieeiucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuifetpfffkfdpucggtfgfnhhsuhgsshgtrhhisggvnecuuegrihhlohhuthemuceftddunecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefhfffugggtgffkfhgjvfevofesthekredtredtjeenucfhrhhomhepvfhhrohoucfnvggsrhhunhcuoehthhgvohdrlhgvsghruhhnsegsohhothhlihhnrdgtohhmqeenucggtffrrghtthgvrhhnpeelvefhkeeufedvkefghefhgfdukeejlefgtdehtdeivddtteetgedvieelieeuhfenucfkphepvdgrtddumegtsgdugeemheehieemjegrtddtmeeiieegsgemfhdtfhhfmehfvgdutdemlegvfhgunecuvehluhhsthgvrhfuihiivgepuddtnecurfgrrhgrmhepihhnvghtpedvrgdtudemtggsudegmeehheeimeejrgdttdemieeigegsmehftdhffhemfhgvuddtmeelvghfugdphhgvlhhopegludelvddrudeikedruddtrddvudegngdpmhgrihhlfhhrohhmpehthhgvohdrlhgvsghruhhnsegsohhothhlihhnrdgtohhmpdhnsggprhgtphhtthhopeefvddprhgtphhtthhopehrihgthhgrrhgutghotghhrhgrnhesghhmrghilhdrtghomhdprhgtphhtthhopehnvghtuggvvhesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehvlhgrughimhhirhdrkhhonhgurhgrthhivghvsehmohgsihhlvgihvgdrt ghomhdprhgtphhtthhopegrohhusegvvggtshdrsggvrhhkvghlvgihrdgvughupdhrtghpthhtohepphgruhhlrdifrghlmhhslhgvhiesshhifhhivhgvrdgtohhmpdhrtghpthhtoheplhhinhhugidqkhgvrhhnvghlsehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtohepthhssghoghgvnhgusegrlhhphhgrrdhfrhgrnhhkvghnrdguvgdprhgtphhtthhopehprggsvghnihesrhgvughhrghtrdgtohhm X-GND-Sasl: theo.lebrun@bootlin.com If HW is RSC capable, it cannot add dummy bytes at the start of IP packets. Alignment (ie number of dummy bytes) is configured using the RBOF field inside the NCFGR register. On the software side, the skb_reserve(skb, NET_IP_ALIGN) call must only be done if those dummy bytes are added by the hardware; notice the skb_reserve() is done AFTER writing the address to the device. We cannot do the skb_reserve() call BEFORE writing the address because the address field ignores the low 2/3 bits. Conclusion: in some cases, we risk not being able to respect the NET_IP_ALIGN value (which is picked based on unaligned CPU access performance). Fixes: 4df95131ea80 ("net/macb: change RX path for GEM") Signed-off-by: Théo Lebrun --- drivers/net/ethernet/cadence/macb.h | 3 +++ drivers/net/ethernet/cadence/macb_main.c | 21 ++++++++++++++++++--- 2 files changed, 21 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h index adc70b6efd52b0b11e436c2c95bb5108c40f3490..d42c81cf441ce435cad38e2dfd779b0e6a141bf3 100644 --- a/drivers/net/ethernet/cadence/macb.h +++ b/drivers/net/ethernet/cadence/macb.h @@ -523,6 +523,8 @@ /* Bitfields in DCFG6. */ #define GEM_PBUF_LSO_OFFSET 27 #define GEM_PBUF_LSO_SIZE 1 +#define GEM_PBUF_RSC_OFFSET 26 +#define GEM_PBUF_RSC_SIZE 1 #define GEM_PBUF_CUTTHRU_OFFSET 25 #define GEM_PBUF_CUTTHRU_SIZE 1 #define GEM_DAW64_OFFSET 23 @@ -733,6 +735,7 @@ #define MACB_CAPS_MIIONRGMII BIT(9) #define MACB_CAPS_NEED_TSUCLK BIT(10) #define MACB_CAPS_QUEUE_DISABLE BIT(11) +#define MACB_CAPS_RSC_CAPABLE BIT(12) #define MACB_CAPS_PCS BIT(24) #define MACB_CAPS_HIGH_SPEED BIT(25) #define MACB_CAPS_CLK_HW_CHG BIT(26) diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c index 48b75d95861317b9925b366446c7572c7e186628..578e72c7727d4f578478ff2b3d0a6316327271b1 100644 --- a/drivers/net/ethernet/cadence/macb_main.c +++ b/drivers/net/ethernet/cadence/macb_main.c @@ -1317,8 +1317,19 @@ static void gem_rx_refill(struct macb_queue *queue) dma_wmb(); macb_set_addr(bp, desc, paddr); - /* properly align Ethernet header */ - skb_reserve(skb, NET_IP_ALIGN); + /* Properly align Ethernet header. + * + * Hardware can add dummy bytes if asked using the RBOF + * field inside the NCFGR register. That feature isn't + * available if hardware is RSC capable. + * + * We cannot fallback to doing the 2-byte shift before + * DMA mapping because the address field does not allow + * setting the low 2/3 bits. + * It is 3 bits if HW_DMA_CAP_PTP, else 2 bits. + */ + if (!(bp->caps & MACB_CAPS_RSC_CAPABLE)) + skb_reserve(skb, NET_IP_ALIGN); } else { desc->ctrl = 0; dma_wmb(); @@ -2787,7 +2798,9 @@ static void macb_init_hw(struct macb *bp) macb_set_hwaddr(bp); config = macb_mdc_clk_div(bp); - config |= MACB_BF(RBOF, NET_IP_ALIGN); /* Make eth data aligned */ + /* Make eth data aligned. If RSC capable, that offset is ignored by HW. */ + if (!(bp->caps & MACB_CAPS_RSC_CAPABLE)) + config |= MACB_BF(RBOF, NET_IP_ALIGN); config |= MACB_BIT(DRFCS); /* Discard Rx FCS */ if (bp->caps & MACB_CAPS_JUMBO) config |= MACB_BIT(JFRAME); /* Enable jumbo frames */ @@ -4108,6 +4121,8 @@ static void macb_configure_caps(struct macb *bp, dcfg = gem_readl(bp, DCFG2); if ((dcfg & (GEM_BIT(RX_PKT_BUFF) | GEM_BIT(TX_PKT_BUFF))) == 0) bp->caps |= MACB_CAPS_FIFO_MODE; + if (GEM_BFEXT(PBUF_RSC, gem_readl(bp, DCFG6))) + bp->caps |= MACB_CAPS_RSC_CAPABLE; if (gem_has_ptp(bp)) { if (!GEM_BFEXT(TSU, gem_readl(bp, DCFG5))) dev_err(&bp->pdev->dev, -- 2.50.0