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 X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=BAYES_00,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6C0A3C43460 for ; Tue, 13 Apr 2021 08:06:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 47317611F2 for ; Tue, 13 Apr 2021 08:06:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240551AbhDMIHQ (ORCPT ); Tue, 13 Apr 2021 04:07:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:48032 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238814AbhDMIHN (ORCPT ); Tue, 13 Apr 2021 04:07:13 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9CB6960FE8; Tue, 13 Apr 2021 08:06:54 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1lWE4S-007BTF-H5; Tue, 13 Apr 2021 09:06:52 +0100 Date: Tue, 13 Apr 2021 09:06:51 +0100 Message-ID: <8735vuobfo.wl-maz@kernel.org> From: Marc Zyngier To: Andrew Lunn Cc: DENG Qingfang , "David S. Miller" , Florian Fainelli , Heiner Kallweit , Jakub Kicinski , Landen Chao , Matthias Brugger , Russell King , Sean Wang , Vivien Didelot , Vladimir Oltean , Rob Herring , Linus Walleij , Greg Kroah-Hartman , Sergio Paracuellos , linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-staging@lists.linux.dev, devicetree@vger.kernel.org, netdev@vger.kernel.org, Weijie Gao , Chuanhong Guo , =?UTF-8?B?UmVuw6k=?= van Dorst , Frank Wunderlich , Thomas Gleixner , Greg Ungerer Subject: Re: [RFC v4 net-next 2/4] net: dsa: mt7530: add interrupt support In-Reply-To: References: <20210412034237.2473017-1-dqfext@gmail.com> <20210412034237.2473017-3-dqfext@gmail.com> <87fszvoqvb.wl-maz@kernel.org> <20210412152210.929733-1-dqfext@gmail.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: andrew@lunn.ch, dqfext@gmail.com, davem@davemloft.net, f.fainelli@gmail.com, hkallweit1@gmail.com, kuba@kernel.org, Landen.Chao@mediatek.com, matthias.bgg@gmail.com, linux@armlinux.org.uk, sean.wang@mediatek.com, vivien.didelot@gmail.com, olteanv@gmail.com, robh+dt@kernel.org, linus.walleij@linaro.org, gregkh@linuxfoundation.org, sergio.paracuellos@gmail.com, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-staging@lists.linux.dev, devicetree@vger.kernel.org, netdev@vger.kernel.org, weijie.gao@mediatek.com, gch981213@gmail.com, opensource@vdorst.com, frank-w@public-files.de, tglx@linutronix.de, gerg@kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 13 Apr 2021 01:07:23 +0100, Andrew Lunn wrote: > > > > > +static void > > > > +mt7530_setup_mdio_irq(struct mt7530_priv *priv) > > > > +{ > > > > + struct dsa_switch *ds = priv->ds; > > > > + int p; > > > > + > > > > + for (p = 0; p < MT7530_NUM_PHYS; p++) { > > > > + if (BIT(p) & ds->phys_mii_mask) { > > > > + unsigned int irq; > > > > + > > > > + irq = irq_create_mapping(priv->irq_domain, p); > > > > > > This seems odd. Why aren't the MDIO IRQs allocated on demand as > > > endpoint attached to this interrupt controller are being probed > > > individually? In general, doing this allocation upfront is an > > > indication that there is some missing information in the DT to perform > > > the discovery. > > > > This is what Andrew's mv88e6xxx does, actually. In addition, I also check > > the phys_mii_mask to avoid creating mappings for unused ports. > > It can be done via DT, using the standard interrupt property, so long > as you use of_mdiobus_register(np). > > But when you have an 7 port switch, and a nice simple mapping, port 0 > PHY using interrupt 0, you can save a lot of device tree boilerplate > by doing it in code. And when you have 4 of these switches, it gets > very boring adding all the DT to just wire up the interrupts 28 > interrupts. I guess this is depends whether the most usual case is to have all these interrupts being actively in use or not. Most interrupts only use a limited portion of their interrupt space at any given time. Allocating all interrupts and creating mappings upfront is a waste of memory. If the use case here is that all these interrupts will be wired and used in most cases, then upfront allocation is probably not a problem. M. -- Without deviation from the norm, progress is not possible.