From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5C7F8C48292 for ; Mon, 5 Feb 2024 16:36:44 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=bootlin.com header.i=@bootlin.com header.a=rsa-sha256 header.s=gm1 header.b=b1RMH9tz; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4TTBpy74nvz3c5y for ; Tue, 6 Feb 2024 03:36:42 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=bootlin.com header.i=@bootlin.com header.a=rsa-sha256 header.s=gm1 header.b=b1RMH9tz; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=bootlin.com (client-ip=217.70.183.200; helo=relay7-d.mail.gandi.net; envelope-from=herve.codina@bootlin.com; receiver=lists.ozlabs.org) 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 lists.ozlabs.org (Postfix) with ESMTPS id 4TTBp812LVz30YR for ; Tue, 6 Feb 2024 03:35:58 +1100 (AEDT) Received: by mail.gandi.net (Postfix) with ESMTPSA id 3C2DE2000C; Mon, 5 Feb 2024 16:35:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1707150952; 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=vq+7j5rxUfbX5WXgjjUMJLefHoCSzp73T0/QzZgsJQ0=; b=b1RMH9tzIEZtvIz/qE6IM+rZBJEFptCrP116L6aKsjBxZ484rRCOYnu6uxibhlNrchhW09 WkDDsVhsWh1GKP4Nznz6+g9CWjpcRCJxrNQhkOr5EOlwa71KLMrKjPqQ+Sdcz7ue+fiEqM qmx8CEztbG97ao52gOnkOnO2oKCzhekdwOEEkwkmz1LFKMydDrhLMeTEHIlH+c1/4qhMZz aoz6csxFiWLYE9CkM/1NncamijP3au1So3PepP7zh3+T6wTMb5s55Dul2asYDf0T73nQmD mS8qDH9dtHEH0IodS1uriDqd4ZPNF/dyV2ZcyRlsId4LhlwXWXTYsfrrTR7ggg== Date: Mon, 5 Feb 2024 17:35:50 +0100 From: Herve Codina To: Paolo Abeni Subject: Re: [PATCH v2 1/6] net: wan: Add support for QMC HDLC Message-ID: <20240205173550.2a6b8f20@bootlin.com> In-Reply-To: References: <20240130084035.115086-1-herve.codina@bootlin.com> <20240130084035.115086-2-herve.codina@bootlin.com> <20240205152208.73535549@bootlin.com> Organization: Bootlin X-Mailer: Claws Mail 4.2.0 (GTK 3.24.38; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-GND-Sasl: herve.codina@bootlin.com X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Andrew Lunn , Vadim Fedorenko , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Eric Dumazet , Mark Brown , Thomas Petazzoni , Jakub Kicinski , linuxppc-dev@lists.ozlabs.org, "David S. Miller" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Mon, 05 Feb 2024 16:49:33 +0100 Paolo Abeni wrote: [... > > > > > > In general is quite bad that the existing infra does not allow > > > leveraging NAPI. Have you considered expanding the QMC to accomodate > > > such user? > > > > I cannot mask/unmask the 'end of transfer' interrupt. > > Indeed, other streams use this interrupt among them audio streams and so > > masking the interrupt for HDLC data will also mask the interrupt for audio > > data. > > Uhm... I fear the above makes the available options list empty :( > > > At the HDLC driver level, the best I can to is to store a queue of complete > > HDLC skbs (queue filled on interrupts) and send them to the network stack > > when the napi poll() is called. > > > > I am not sure that this kind of queue (additional level between always > > enabled interrupts and the network stack) makes sense. > > > > Do you have any opinion about this additional queue management for NAPI > > support? > > With such idea in place, what HDLC-level data will be accessed by the > napi context? The RX interrupts will remain unmasked after the > interrupt and before the napi poll right? That would be > problematic/could cause drop if the ingress pkt/interrupt rate will be > higher that what the napi could process - and that in turn could bring > back old bad livelock times :( Indeed. So the best thing to do is to keep this driver without NAPI support. Best regards, Hervé