From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from vps0.lunn.ch (vps0.lunn.ch [156.67.10.101]) (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 878812472B0; Wed, 16 Apr 2025 12:27:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=156.67.10.101 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744806471; cv=none; b=qZBlT0oNGyGPiXNljfDMLal2mQwfhFQbs2kumjGFQ0pK8LWsTrUpgR660xe8Jkrll57wdVADIAyEUZl65oZVaRuc5m+syPbyRhdrF8N+EBRYGqFhfbE/XU659cacB37cx8eB2dcoAzr86zJ+OU0LrNagAInV0/A51vDUVcL9Dr4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744806471; c=relaxed/simple; bh=2Z9dMh3cUftNywdxpqLdiZhzIykbnecaYABQWReuukc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=PpSSYJ+jFqLB6EE1QdOzOgboez8k5eggUDsFGGGKt9hECi6trLjespJ7nJUkJ5LdiwI1QGIcdqo2Zx7PLBoMrZ0RIaptV91VxLPd+IEGvimzjkELAMvhZgTCrvXo2FMKtOYsC/ezoDNqa/1CXqJnUw3kOn/cae3ddJvn9IC82EY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lunn.ch; spf=pass smtp.mailfrom=lunn.ch; dkim=pass (1024-bit key) header.d=lunn.ch header.i=@lunn.ch header.b=glWcQhDU; arc=none smtp.client-ip=156.67.10.101 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lunn.ch Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lunn.ch Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=lunn.ch header.i=@lunn.ch header.b="glWcQhDU" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lunn.ch; s=20171124; h=In-Reply-To:Content-Disposition:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:From:Sender:Reply-To:Subject: Date:Message-ID:To:Cc:MIME-Version:Content-Type:Content-Transfer-Encoding: Content-ID:Content-Description:Content-Disposition:In-Reply-To:References; bh=M6LZ4xvneSkqTz22l3dMKDkqWPVz423Fwa7KsioWGuA=; b=glWcQhDU7brC7S3hO/V50YBI06 VnjiupGMv6jbZ+aQIKjz2lzfyyldKifS+Dohd+2omPCSVsilyPi0iHjFgp/qCIXeqg4Z57ONQ1u0v bcRxmL2mht1t1baiQinA8cC1MwRbseAE5DxgbA6Tp14Aelkj4ugbrgOkPYsAWhON1S28=; Received: from andrew by vps0.lunn.ch with local (Exim 4.94.2) (envelope-from ) id 1u51rc-009cKD-AE; Wed, 16 Apr 2025 14:27:36 +0200 Date: Wed, 16 Apr 2025 14:27:36 +0200 From: Andrew Lunn To: Fiona Klute Cc: netdev@vger.kernel.org, Andrew Lunn , Thangaraj Samynathan , Rengarajan Sundararajan , UNGLinuxDriver@microchip.com, "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-list@raspberrypi.com Subject: Re: [PATCH net v2] net: phy: microchip: force IRQ polling mode for lan88xx Message-ID: <89826aa3-adc6-4278-a85a-b72ba8132add@lunn.ch> References: <20250416102413.30654-1-fiona.klute@gmx.de> 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: <20250416102413.30654-1-fiona.klute@gmx.de> On Wed, Apr 16, 2025 at 12:24:13PM +0200, Fiona Klute wrote: > With lan88xx based devices the lan78xx driver can get stuck in an > interrupt loop while bringing the device up, flooding the kernel log > with messages like the following: > > lan78xx 2-3:1.0 enp1s0u3: kevent 4 may have been dropped > > Removing interrupt support from the lan88xx PHY driver forces the > driver to use polling instead, which avoids the problem. > > The issue has been observed with Raspberry Pi devices at least since > 4.14 (see [1], bug report for their downstream kernel), as well as > with Nvidia devices [2] in 2020, where disabling polling was the > vendor-suggested workaround (together with the claim that phylib > changes in 4.9 made the interrupt handling in lan78xx incompatible). > > Iperf reports well over 900Mbits/sec per direction with client in > --dualtest mode, so there does not seem to be a significant impact on > throughput (lan88xx device connected via switch to the peer). > > [1] https://github.com/raspberrypi/linux/issues/2447 > [2] https://forums.developer.nvidia.com/t/jetson-xavier-and-lan7800-problem/142134/11 > > Link: https://lore.kernel.org/0901d90d-3f20-4a10-b680-9c978e04ddda@lunn.ch > Fixes: 792aec47d59d ("add microchip LAN88xx phy driver") > Signed-off-by: Fiona Klute > Cc: kernel-list@raspberrypi.com > Cc: stable@vger.kernel.org Reviewed-by: Andrew Lunn Andrew